There is no reason to sell off your models. As long as there is an influx of new players (which is a good thing) stores will most likely continue to run 35pt tournaments. I have spoken to several new players that do find 50pt games intimidating.
50pt games are my favorite as well. However, I don't think there will be an overall increase in the size of tournaments. I do like the idea of including giant based models in 50pt games as it seem to bring the cost/value ratio into the sharpest focus. If you are someone who is interested in playing large venue cons, then you'd best start practicing 50pt games.
If one isn't inclined to play in tournaments then continue on as normal. You will always be able to play a 35pt game.