Does Toei really need this? Tsuburaya is promoting Ultraman to the West, and everyone who is seriously interested in him will sooner or later come to Rider and Sentai. Why spend money, share profits and take risks when you can get the same result without doing anything?
The main problem of PR: copying is pointless, doing your own is unprofitable. And until that changes, the franchise is doomed to suffer.

It's still a large hole in the market that relies entirely on their direct competitor sparking enough interest.
While Sentai and KR is easier to access now that it's officially streamed, what's being streamed are older seasons with no merch to back it up.
The Henshin Hero genre is ride or die on toy sales, so residuals from DVDs or ads on streaming are nothing compared to getting people to buy the mechs.

If a company in the US isn't going to market Power Rangers, Toei should at least make a marketing push for their Sentai subs.

To add onto this, the question in itself is a loaded one. It'd be like asking "Do we really need official subs for Toku shows? Fansubs exist afterall!"

But even ignoring all that, why should fans of Power Rangers(hi, we exist!) have to go without simply because it's based on something else? Or should the US Godzilla films stop getting made because Godzilla's a Japanese property?

People often forget that not only is PR based on Sentai, but Sentai continuously grows thanks to ideas it gets from Power Rangers. They work in unison, not against eachother. And simply killing Power Rangers off not only means a smaller fanbase overall, but less creativity coming in for the market.

People still like Power Rangers. Talking down to them about the whole situation does nothing.

You're going to have to give me examples of that later point cause I've never heard this being the case. Like sure, sometimes some ideas might be similar, and sometimes they might directly take something like the SPD battlelizer, but otherwise I don't think Toei or any of the creative teams on Sentai cares about what happens in Power Rangers.

And to address the Godzilla comparison, the US Godzilla films are still at least wholly original, whereas Power Rangers to this day still takes and bases its footage around Sentai. It's literally within the DNA of the franchise and every attempt to move away from it hasn't worked. Sentai can exist without Power Rangers, Power Rangers can't exist without Sentai.

I'm not saying people can't like Power Rangers. I just don't think the franchise has any shelf life in the current media landscape.

Koichi Sakamoto built his entire career off of Power Rangers, only becoming a prominent director thanks to his time with Saban and Disney. He even went so far as to include Power Rangers references in the episodes of Gokaiger that he directed.

There's also Zenkaiger, wherein we can thank Juran's' entire existence to PR; Mighty Morphin' specifically. Those are just the two examples that jump to the front of my brain.

Toei does infact care about a property that serves as a direct representation of one of their most prolific franchises.

How unfortunate, I wasn't aware he was so influential in PR's improvement. It's tragic enough that he died, but even worse that his vision died with him. R.I.P.

Gobusters' Morphin' Brace says, "It's Morphin' Time!" and their enemy is a computer virus like Venjix.

Zyuoh The World is a normal human who was brainwashed in to a villain before redeeming himself like Tommy.

Kyuranger is set in a dystopian future alternate dimension conquered by the villains like RPM and the main villain is a spirit that corrupts the host like Dai Shi.

Lupinranger and Patranger have powers from the same source like how Ninjor created the Power Coins for Mighty Morphin' and Alien.

Strongest Battle is set on Planet Nemesis and the villain is called Rita.

Kirama Silver arrived on Earth from Crystalia (although originally from Earth) like how Orion came from Andresia.

Sempaiger are a group of 10 Red Rangers who fought the remnants of a defeated villain faction like in Forever Red.

Kuwagata-Ohger and Ohkuwagata-Ohger are long-lost brothers with one of them having memory loss like the relationship between Brody and Levi.

Akibaranger had the Powerful Rangers.

To add to what DreamSword said, not only is Zenkai Juran based on Zyuranger, but also Super Zenkaizer. I know Zyuranger was popular for its time, but this seems way too deliberate to not be a Mighty Morphin' reference.

To be fair, a lot of those examples are just similarities in 2 long running franchises.
To say something like a brainwashed villain becomes a hero or an amnesiac reunites with their long lost sibling is a PR homage is a massive stretch.

That's not to say some aren't honest to goodness PR references (It's Morphin Time and the mech system being called Megazords in Go-Busters, Zyuran's entire existence, and the Powerful Rangers), but a lot of those are just circumstantial similarities.

Also, losing the Western market would be a massive fumble for Toei

Yeah, a number of those are just cute references/nods, or just coincidentally similar ideas. If we're talking about Sentai being creatively inspired or influenced by Power Rangers, I really can't think of a single noteworthy example.

I would argue that the prevalence of the sixth ranger archetype exists almost entirely because of Power Rangers. The Green Ranger was immensely popular, and Dragon Ranger was the FIRST sixth ranger, at least the first to actually stick around for more than one episode.

Zyuranger is obviously still the basis for the concept, but you can see there was still some hesitancy to the concept through Kakuranger and Carranger, which didn't really have proper sixth rangers. This also happened during the time where Power Rangers and Sentai were airing alongside each other, so it's highly likely that this was a massive factor in sixth rangers continuing to be a thing, and reaching the level of marketing that they have today.

Power Rangers has also definitely affected anniversary seasons due to how the two franchises have lined up, even up to Zenkaiger. Gaoranger's anniversary tribute was a movie, Boukenger limited its references to the monster designs, Gokaiger was only originally going to have anniversary episodes for the series that had mechs based on them, which were all ones that got adapted into Power Rangers, and the only Zenkaiger member not based on a Power Rangers adapted series was Zenkaiser.

I know it's silly to say that Gokaiger made steps to ensure that it could be adapted into Power Rangers considering how it went, but I really doubt that they would have expected it to go like it actually did.

I think Power Rangers has had a marked impact on Sentai from a production level, if not a story one. Power Rangers being made is the exact point where Sentai stopped being able to make things like Jetman, where it shifted to more generally family friendly material. Some people probably don't consider that a good thing, but its definitely something that has worked out business-wise.

If Hasbro sells the franchise, who is most likely to buy it?