Kelsey Grammer was a fun fit for Beast in Xmen: The Last Stand, he wasn't given too much to do granted, but he certainly was a very distinguished version of the character.
While, Nicholas Hoult seems to have his stamp on the character currently, it looks like Grammer would be well up for coming back. Speaking toIGN at NYCC, the actor revealed it was his idea to come back as the character briefly in Days of Future Past. It seems Grammer genuinely enjoys playing the role too as when asked if he would come back if the opportunity arose, he said:
Yeah! I would love to do another one, because that character's great.
Considering the state of the X-men movies now, specifically the older timeline, it is hard to know exactly how he could come back, unless he is secretly in Logan (which would be a neat addition). Still, if the chance ever came up, I'd totally be behind seeing him again.