Does future floor gloss crack over time?

Several reasons for this:

It shouldn't as it self levels, as in I dip canopies it it, then (important) wick away the excess by sitting it on lint free tissue for a few moments.

Gloss coat/Future put on too thick.

Finish coat not properly cured, some paints can take weeks.

If the underlying object is flexible (most polythenes) or not properly primed, this can cause the top coat to crack or flake.

I think there are several different formulations of Future out there, because I know lots of people here have never had issues with it.  I, on the other hand, have had it start cracking after only a few weeks when used as a clear coat prior to weathering/decaling.  This was after airbrushing it over fully cured paint (1 week or more of curing time in all cases).  The only way I found to prevent it was to put a lacquer clearcoat over the top of it, which makes me wonder why I wasted the extra time putting the Future on if it can't do the job on its own.  Also haven't found my Future to be of much use for dipping canopies, as it reacts really badly with my Bob Dively Liquid Mask.  I'm in the camp with those who say "Future is for floors".  For me, lacquer clear coats for model bodies, and my Novus polishing kit for canopies have proven to be much better alternatives.  That being said, Future is the absolute best adhesive I have found for small, clear parts and small, flat PE parts where complete clarity after drying is critical.  So, I still use it, just not for what many use it for.

From what your saying  sounds like it can, as you mentioned, some have had that happen to them.

The iteration I have is called Pledge Floor Care and I haven't had any issues with it ( I notice it's also no longer on the shelf at my local store). It might be worth noting that I also give my dry times of base coats a boost in a dehydrator at 108f as a general routine.

It's not the only clear I use though.

I've used it for at least a decade and never had any problems, including cracking. That includes using it as a shiny top coat for decals and weathering, coating clear parts and trying to get some shine on my worn out kitchen floor. The last time I bought some (several years ago) I wasn't sure I had the correct product so I unscrewed the cap and gave it a sniff. 

Never personally had it happen in over two decades of use.

But as many times as its formula may have been 'tweaked' by the manufacturer...and considering the ever-wider variations of chemistry found in modern model-finishing products...I'd almost be surprised if it hadn't happened.

The thing is, I've been working off the same bottle of 'Future' (still called that, then) for maybe as long as ten years, with not a single issue; it may be that when the time comes to replace it, I'll be in for that kind of nasty surprise.