So i'd be in the same vein as Grease Blizzard.

Maybe he gets his own WRB and he becomes a Falchion but repainted in his color scheme? That does sound kinda cool come to think of it.

I remember reading a joke for a Super Hero Senki scene where Mei gets to grab Kurayami and it tells her that she'll be blown away like usual. Then Touma, Rintarou, and Kento fight with their respective swords. Mei doesn't wanna get blow away and she goes "Agh, me too!" so she grabs Kurayami, transforms, tries to fight, but end up being put in the future she saw and being blown away.

I hope for Espada’s upgrade to be like Tategami Hyoujuu Senki in a Grease Blizzard-vibe, where his armor is coloured black and gold.

For Calibur… who to take the place of Hayato, Kamijo and Kento?

Oh my word, that would be the most amazing and hilarious thing ever. As much as it definitely won't happen, if someone told me it did, I might just watch the whole movie just for that. Just the Idea is making me laugh. XD

Maybe I'll watch it anyway. I haven't really thought about it yet...

His Alter Ride Book slightly changing when in the Haken BlaDriver, that does sound cool.

Maybe call it Desaster Hybrid? I read somewhere he's supposed to be a mix of all three types of Megid, so it would be fitting.

I feel like it'd either use the Kurayami or Ikazuchi Wonder Ride Book, much like X-Swordman did for Saikou.

Espada Upgrade: Either a book based off of Dragonic Knight or Tategami Hyoujuu Senki. Cause it oughta give anything with an 1001 Arabian Nights vibe.

Calibur Upgrade: We may not see Hayato return as Calibur, fighting alongside Touma & the others. Kurayami oughta be passed onto a new candidate. As for the upgrade, I picture something based off of Primitive Dragon - Jigoku Dragon!

Apparently, the Toei online store has leaked that the next spin off will be “Kamen Rider Specter x Blades”