We just have been in a situation, when we saw many ServerCrashProcedure to be blocked, because of the AssignProcedure is blocked because of the missing .tabledesc files.
In our case it was OK for us to get rid of these tables and we were able to use setRegionState to move all these regions to FAILED_OPEN state, then disable and drop the tables. But this took a lot of time and we might not always have the option to drop these tables.
HBCK 1 had a functionality (fixTableOrphans) to regenerate the table descriptors "according to the memory cache or hdfs table directory structure". We should investigate if we can implement something like this with hbck2. We might not always be able to reproduce the table configurations, but we can probably make a "basic" one.