I don't know if this ever got mentioned before, so don't shoot me just yet. At the end of the series, the black hole was finally stopped by Primus and the fully powered Omega Lock which had all it's Planet Keys. We know the black hole would have consumed all of creation and only came to be when Unicron was completely destroyed. Unicron and the black hole were said to symbolize the balance of good and evil, at least in this continuity. Without either, things would not be in balance. It would appear with no apparent or immediate threat that things are out of balance even if things are at peace. Did Unicron inadvertently or subtly get recreated with the black hole being stopped (and Galvatron being destroyed shortly thereafter)? Or could another huge threat beyond the scope of the Decepticons emerge as a result?
I guess Unicron would have come back at some point in the future... But for then, the Unicron Trilogy was done and finished and everyone lived happily ever after.