I've read the 50 slots number a few times, but never anywhere remotely official so I'm not sure I believe it.  Generally there are about as many slots as people who want them.   
  
There seems to be a feeling among cadets that being an AF pilot isn't fun.  And/or worth the 10 year commit.  The issue has become a concern institutionally, it's a big part of why the powered flight program exists.  They are also adding more airmanship programs.  For example, as in days of old everyone will take at least a few glider rides.  Everyone will get a few T53 rides, etc. 
  
Total aside, but I recently came across an old program, they used to have T33s (and later 37s I believe) over at Pete so that cadets could go fly during their free periods.  That would've rocked.