It's hardly unprecedented to split up a long and challenging story into multiple parts, even for Japan.
That UBW movie sucked is rather secondary to the fact that many adaptations suffer from being cut down and crammed into a single movie. Making a long movie at the standard we've come to expect from Ufotable (I'm guessing) would be a huge strain for them. Let alone 3 hours or so long. Which I'm still not sure would do Heaven's feel justice.
The many suggestions of 2-3 movies don't sound unrealistic.