Can he act again?

Not at the moment, that's for sure.

BAD CGI RUINS MOVIES!!!

He's voice acting again, he got his voice back last year, but unless he plays someone who has had a stroke then he's unlike to be doing anything live action for the time being.
He's wheelchair bound and has lost a lot of muscel tone done one half of his body.

He could do a rear window remake.

There's a clip posted from the Tony Awards where Mr. Curry can be heard speaking:

https://www.youtube.com/watch?v=BMgXboVyxY0

He's slower for sure, but his voice is remarkably clear for a man whose body was so affected by a stroke. He might be more limited in the voice work he can do, as I don't think he can play anything but an older character, but he by no means is unemployable.

As for live action films, I think that even before his stroke Mr. Curry had largely retired from films and was devoting most of his later years to voice work. I would be surprised if at the moment he had any desire to appear on camera, but I think in the right role he could still do it.

He rather reminds me of Vincent Price in the last decade of his life, who had a similar slowing of faculties but still managed to work in a number of forums.

Yes i think Vincent price, Much like Bob Hoskins, had parkinson didn't he?

Yes, he contracted Parkinson's in 1989, but also suffered from really crippling arthritis, emphysema, and eventually lung cancer. It's actually quite remarkable that he was involved in as many projects as he was toward the end.

As for live action Tim Curry will be in the new TV version of Rocky Horror as the narrator, which is awesome and makes me more excited to see it