Well, as long as noone conclusively wins outright, we will have a standoff that will leave Miners on Legacy Chain very much obliged to slowly move towards UASF chain with the growing risk of reorg.
Doubtful. I would expect that the legacy chain will leave the UASF chain in the dust, with no hope of ever coming close to such reorg. Even if it did, however, there are trivial means to ensure such a reorg does not occur (e.g., invalidateblock).