I'm being realistic. The Samurai Megazord costume is more likely to still be around, while I'm pretty positive the Astro Megazord costume has been scrapped already.
It would be much cheaper to just get the Shinken-Oh suit and make their own footage to replace FlashKing.

It could be pretty cool.

Both appeared in 199, among every other giant robot and Variblune & Varidreen, which happened only a couple years ago. I'm sure that, if most or all those older suits and VTOLs were made from scratch and then scrapped post-production (assuming that the original suits and VTOLs weren't kept at all) Toei wouldn't rebuild 6 mecha suits (Daizyujin exempt, because Saban would probably prevent destroying that suit) just for a team up. That costs ¥, and a large company like Toei is most likely savvy enough to not waste materials that would be used later.

Of course it could, everything is better with Shinken-Oh!

A lot of 199 was stock footage, though.
And you overestimate how little regard Toei holds for their suits, shameless cutting up old ones to help make newer ones if they're not just tossed to begin with (Though, they have been saving them recently, so perhaps if Astro appeared outside of stock footage they might still have it).

Yeah the suits in 199 that aren't from at least the 10 most recent shows are ALL a mix if CG and vintage footage that's been spliced together. Creative angles and shots seal the deal, making you believe they're there when they aren't.

That.. is heartbreaking, is what it is. They should be preserved, placed in airtight containers, and kept in a museam.

It's unfortunate Toei cares more about their Edo set than their iconic suits, but it is what it is.
But you think if they ever made a Toku/Sentai museum, they'd use the suits rather than just build statues for them?
(Also, how badass would it be to walk down a hall filled with all the Mechs from Battle Fever to now?)

Very Badass is the only answer to the question. Statues of the Sentai Suits with a giant statue of their Mech behind them? Hell Damn It Yes.

i think most of them are in a museum due to daizyujins orginal costume is in the toei heros museum so i thin the others are as well so they had to remake the other 2.

Those are statues/"miniatures" used for static posing. Not the actual suits worn by the actors.