Can be, you cant trust the US in this anymore. However, the fact that they start to propose such things that they would not dare to propose before is a good sign. We have thus secured a nice bargaining chip it seems.I dont think US would ever make YPG leave those "safe zone". Their idea is probably to symbolically let some Turkish soldiers into the bases they built in ypg controlled areas. Their is no way they can tell YPG to get out of Tel Abyad, Kobani etc.