Right now the only information they are giving is that they are gone for now and no word on why shows get cancelled day of, but have heard technical issues cited the most when talking about probable causes.
That being said, my opinion is now that Frozen Live isn't quite new, they probably don't have a huge need to curb demand with FPs. Aladdin ran for years at the Hyperion and only started offering a FP once and end date was announced and saw a spike in attendance. Even with a FP for Frozen people were lining up 60-90 min before the showtime so it didn't really save you time. Now that it appears that the demand has gone down for it, they are probably able to accommodate all shows with standby seating not and saving the money to staff a team to man the FP booth from park opening until all FPs are gone (which could have been as late as 30-60 min before the last show of the day meaning they were staffing a full shift just to sit there and man FP booths that weren't going as quickly as possible).
Again this is all my own conjecture, but bottom line, you should be very fine to do standby. If you're a fan of Frozen, it's a great one. I would just recommend that if it is a priority you take the time to wait before the show ( at least 45 min, if not 60 min). It's also an hour-long show so definitely a good chunk of time commitment, but again if you are a fan of Frozen, you'll love it. Hoping you'll be able to catch a show on your trip! I'll send pixie dust and good thoughts your way for it!