Would they allow a majority of the Knesset be muslims?
That’s like the rats letting the black caucus lead the party.
Well, there are elections. So, it depends on who is voted for.
Israel has a higher birth rate than most developed countries. I suspect that the birth rate is highest among Orthodox-leaning Jews, and Arabs. The number of secular Jews is probably going down.
Israel limits the number of Arab MKs, so they will never have a majority.