How long left does Israel have as a nation?

Israel most likely has a long, long while. I wouldn't bet on even living to see its end.

While some people are concerned about demographics, chances are that Israel's Jewish majority isn't going to change. Still, ignoring that and assuming Arabs become the majority, then we can expect an increase of Arabic use on the streets of areas not traditionally Arab such as Tel Aviv. Arabic is still an official language of Israel today so official documents can be obtained in it, and street signs have it on them as well so that won't change. Also assuming the Jews aren't kicked out, I wouldn't expect Hebrew to disappear, since the Jews will continue using it in their homes and businesses if able.

Pretty long. Arabs may be multiplying like rabbits but the religious Haredi Israelis have even more kids per family. The Jews will always outnumber the Arabs in Israel, but the secular Israelis will become a minority.

When the Haredi Jews become a significant majority we'll start to see religious governments getting voted in. Israel will change drastically, but it will still be Israel.

Pretty long. Jews will always outnumber Muslims in Israel. Israelis are surrounded by hundreds of millions of Muslims, what's a few million more? :)

Many jews spoken Aramaic a sister language of proto semetic , unlike Hebrew, Aramaic always survived although it died out among many speakers choose to speak Arabic rather than Aramaic.

It is very unlikely to happen, unless Israel will do some very stupid action like letting millions of "refugees" (who were born, and their parents were born, in countries like Jordan and Lebanon) to get into the country.

And even if it will happen, the Jews will keep their tradition, like we always did. Hebrew will not die, obviously.

Minorities isn't about numbers, it's about political power

Minorities in any country are typically synonimous with their minor political power. They can be 90% of the population and still be called minorities because of the way of life they lead by making choices on the expense of others.

Israel will always exist and it has one of the strongest nations in the world.

Forever.

The promise of G-d for the eternity of Israel will last forever !!

Sorry to say that it will take about 20 more years of tyranny before the illegal, immoral and unethical state breathes its last evil breath.