If I believe the trainer simulator that I just tried, if you do that, you will remain in SRS forever.
The airplane will not accelerate nor will it let you pull speed and choose another one, except if you engage another vertical mode.
Apparently, if you set the altimeter target above your altitude too late, that is after the acceleration altitude, the clb alt blue modes do not engage, you remain in SRS but in one case I simulated I kept SRS alt blue. So when the airplane reached the level I had chosen, the airplane levelled off from SRS to ALT*.
It sounds realistic but that may just be the sim.