Like NAM says, as long as time continues to move forward everything will become C&R as it meets the 50 year requirement. Assuming they aren't destroyed, lots of older service pistols and rifles should become available as their respective countries upgrade (full auto excluded). For example, in the next 10 years, more PP/PPK and STAR pistols will fall under the 50 year rule.
That being said, it is my opinion (which I don't like), that eventually someone will change the law to say that a firearm must be on the "list" (either by make/model or serial number) to qualify as C&R. I say this because at some point, AR-15s, AK-47s, semi-UZIs and so on will fall under the 50-year loophole (that's what it will be called). Uneducated types will see C&R transfers as too private and too unrestricted (no background checks) and there will be a big push to get these types of weapons under 01 FFL transfers (assuming they're not already banned). As C&R collectors, we need to make sure when AWB-II comes around, our interests are represented as well.
LL