I'd be interested to see how far this can be taken...

Why not make pointers just 4 bits, giving them only 15 possible memory locations they can point to? Then try to allocate the thing they'll be pointing at in one of those 15 locations. Reserve the 16th location for some kind of backup data structure which can point anywhere.

Clearly it isn't branchless, but I would guess that most codepaths would either always be able to make use of one of the 15 locations, or would never be able to, making branches predictable.