The problem with full implementation of Palestinian’s already in Israel to be citizens is the population is so huge that they would have a majority in voting in the Knesset. It would wipe out the Jews majority.
Arabs in Israel are citizens, and citizenship was offered to Arabs in East Jerusalem years ago, and I believe the offer is still in effect. I suspect you’re talking about Arabs in what’s called the West Bank. That’s up to Israel, but I think Israel is content annexing the settlement blocks and Jordan Valley, leaving the rest of the Arabs to their own devices. At the end of the day it’s Israel’s choice.
That has been disproved. The birth rate issue is not working against Jewish Israelis.