Look, be realistic. The Jews are not a monolith of Zionists. They do not wake and sleep and eat and live to serve and support Israel. I don’t know why you attribute this level of commitment to them, even though the Qur’an is filled with stories about their dereliction of commitment to anything other than their own self-interest and personal benefit. Allah told you that their hearts are divided, and they are; although you think they are united. The fact is, most Israelis are not die-hard Zionists, and most Jews in the world are not Israelis, and have no interest in being Israelis. The real lunatic Zionists are the ultra-orthodox Jews, and they are a very small number, both globally, and within Israel.
The largest wave of Jewish immigrants to Israel in recent years came from the former Soviet Union, as a result of the collapse, and subsequent economic crisis in those countries. They were opportunistic, not ideological immigrants. Until now, they still regard themselves more as Russians than as Israelis, and their “Jewishness” is largely inconsequential to them. If they have better economic opportunities elsewhere, or if the situation inside Israel becomes too difficult for any reason, they will leave.
There are a lot of domestic problems in Israel, including ethnic tension between various groups. There are many ways we could potentially exacerbate these tensions, and create incentives for certain groups of Jews to go back to their home countries. This would further magnify the demographic problem the Zionist project is facing.