David Raya and David de Gea are the only alternatives to be rumoured for Bayern Munich to replace Sommer. Actually it depends on whether he leaves or not. For now as you have also mentioned his name is called with Inter. If Sommer goes there there will be a serious need of a new goalkeeper.

Because Neuer can't start playing as of the beginning of this season. Even if he returns I have big doubts about him to continue from where he left. He has got really old (37) and I think it is time for Bayern Munich to replace him permanently.

Between the two alternatives I mentioned my preference would be David de Gea.