This is interesting... Could the possibility of the Universe rather than expanding infinitely somehow invert onto itself? I offer this argument from a YouTuber as a possible proof that redshift has been mis-interpreted as an accurate way to gauge distance in a fixed Euclidean space. ( if that is the correct term to use as I have not figured out if redshift is parabolic in nature or not )
There is some interesting statistical information here, but this guy is way too crackpot-like in a few regards for my liking - he has his little catchphrase "The Big Bang is Bung" which he seems to like the sound of, and he provides no other evidence to support his claims about quasar redshifts. It's true that the apparent correlation he presents between redshift and separation is interesting, although there should be much more data available now on distant objects which should support his suggestions. Additionally, it could be disingenuous to assume that the only factor involved in separation is distance - remember that the Universe was much smaller in the past (according to the Big Bang model) and so it may be unreasonable to assume that mater distributions have remained unchanged over that period. The correlation could in fact be very strong evidence
for the Big Bang, if argued another way - hence the need for other supporting data.
I have my own concerns about using redshift, although they are more GR-based and involve frame-dragging-like effects that appear to have been neglected in certain astrophysical calculations.
Additionally... This paper on Pair Production suggests that the Universe is capable of producing matter from energy. If the mechanism exists... Is it a safe bet to think it's happening?
http://adsabs.harvard.edu/abs/2003hep.ex....6017L
For some reason the full text link wasn't working from that page, but from the abstract it doesn't look like they're claiming any unusual matter creation events... mass and energy are equivalent and largely interchangeable given the right conditions, but you can't create matter from nothing (in the case of the LEP the 'extra' matter was created from the kinetic energy of the electrons and positrons). I don't mean that to sound patronising if you know all about this already, but I have no idea how much you do know on the subject!
The vacuum produces particle-antiparticle pairs constantly (which actually have measurable effects - see 'loop binding corrections') although these quickly annihilate and return the energy 'borrowed' after a very short space of time. These processes would be subject to heat death as well.
The 'third option' you refer to is the 'Big Crunch' where there is enough mass-energy to counter the expansion of the Universe and space-time begins to collapse again. This would essentially be the reverse of what has already happened, ending up with everything collapsing into a singularity-like object. Models predicting this behaviour can be subject to problems such as 'black hole disease', however, where black holes produced in the previous Universe can survive the 'crunch' and pass into the new Universe. This would quickly end up with a Universe made of nothing but supermassive black holes, which is not what we see today.