Most make this their MWS, and stay.
Some,... not many,... will move on elsewhere. However, very, very few go back to their MWS. I can't think of anyone in many years that has done so.
About 4 went to the 89th, but not from Beale: they left Beale and went to Staff or ROTC, etc... then to the 89th.
Usually 1 will go to TPS every 1-2 years.
Many will go on to some interesting non-flying assignments (PhD program, Olmstead, off-the-wall-and-no-one-has-heard-of-it-PME in residence, NRO, etc...
Ill say it again: this is not a cure-all for the evils of the Air Force. Many/most pilots would probably not like the U-2 program. Everyone has their own reason for volunteering.
Apply because you want to be in the U-2,... not because you want to escape where you are.
If you don't have a desire to be in the program, you probably won't like it.