Colonizing and terraforming every single rock in the solar system increases the available land only by a factor of three: https://xkcd.com/1389/
There's just no way every commoner gets their own Caribbean cabin. Unless we find some unlikely physics hack in the last few vestiges of scientific unknowns, any interstellar travel seems impossibly difficult.
An alternative future: we live forever as brains in the vats, plugged into infinite virtual worlds devoid of scarcity, life-threatening danger or physical constraints. Most of the human activity takes place there, with occasional interactions between the virtual and the real. No new physics required, just a series of incremental improvements in biology and computing.
If we're being cynical, it's trivial to ensure that every commoner gets their own Carribean cabin - just reduce the number of commoners by a few orders of magnitude. After all, with some technological advancements, you would not need huge numbers of commoners just for their labor.
A stable future can plausibly take many forms, not all of them are nice.
Is that your candidate for the Great Filter?