Props wont make a comeback. RJ's are slowly taking away more and more of the market. The major airlines keep giving more and more of their routes to their regional RJ's. So they have lower costs and more frequency. So if anything the number of RJ's will increase more and more. Take a look at the airports now, ten years ago their were almost no RJ's at the big airports. Now look at say Chicago where the RJ's come close to out numbering the mainline planes. All the mainline airlines appear to be moving away from the unprofitable domestic flying in favor for international and cross country. Why fly a 737 between city A and City B when you can use several RJ's with their cheaper operating costs and regional pay scales.

The mainlines wont let props return, because then they would have to take back all the flying they didnt want to operate before.