Personally, Xenoblade felt too long for me. I don't have the time or attention span to invest in a single game for 100 hours. Skyrim is probably one of the best and biggest RPGs in recent memory. I played about 20 or 25 hours worth and haven't touched it since. There are other things I want to play.
So if the Last Story comes in at around 25-30 hours, I'll be fine with that.
Check out my Youtube Let's Play channel here.