Rails?
No current rifle design was designed with rails. Lest we all forget, those uber-tacitcal M4 carbines are little more than 1965 M16A1s with shorter barrels and rail handguards bolted on.
Rail handguards can be made for any design out there. I've seen them for the M1 Garand, for crying out loud.
The M14 is making a comeback in the military for the DMR program because they still have M14s in the inventory. Personally, I'd like to see a tricked-out, free-floated FAL pressed into the role, but the Pentagon stopped returning my phone calls.
They may be experiencing a jump in civilian popularity becasue Springfield came out with the SOCOM. People these days like shory, handy carbines. We're all convinced we're going to have to do building sweeps (myself included; my FAL recently came back with a 16" barrel). Rifles are just handier that way.
As for the price...
Why is it people complain about the price of every rifle out there except the AR-15? Why is $1,000+ for an M1A, made by one company, too much? How about $800 for an AR-15 that the company whose rollstamp is on it didn't actually produce? Most AR-15 makers farm out their production to subcontractors. Given that, and the volumes of production, a stock AR-15 should cost like $500, same as a high-end AK. The cheapest quality AR you'll see is probably $699 for a DPMS, though. Bushmaster costs more. Colt, Rock River, Wilson, Knights Armament...cha-ching!