If a CP can't be built, it should expire and not be reissued for 10 years. Just because a station can be "shoehorned in" engineering wise doesn't make it is viable.
That's pretty much what we've got now. The FCC has been holding FM band auctions every 5 years or so. If someone bids on an allocation, and does not build it or turns back the license, it gets auctioned again.
But with a few exceptions, the facilities that are being auctioned are poor facilities in very rural places. In the last auction, there were two allocations sold in Grand Portage, Minnesota, deep into the arrowhead along Lake Superior. Both sold for under $5,000.