Does an uncoordinated turn increase stall speeds? When you do cross control for crosswind landings in GA aircraft like C172, should you be worried about higher stall speeds during flares?
First question, yes. For two principle reasons: instrument error and a change in relative wind across the wing. The increase in indicated AS would be small.
Second question, not a factor. During the flare, you are close to the ground, and the AOA is mostly controlled by feel, sink rate and all the other things that factor into that complex maneuver. So if the speed were slightly higher, it probably wouldn't make a difference.
But let's talk practicality. When landing a C172 in a direct crosswind of 20k or so, I would add 5k to my speeds, and if the winds were gusty I would add accordingly (like 1/2 the gust factor approximately).
It is better to focus on having a stable approach with good AS and pitch control, than it is to fret over a potential 2k indicated stall speed differential. Besides, in ground effect the numbers change as well.