A new Palestine would be a more formidable military foe than Egypt, Jordan and Syria were in the past?
Actually, it could be. Firstly, it would have an extensive border with Israel, leading to a high probability of extensive infiltration. It would be able to constantly infiltrate Israel, especially through built-up areas such as Yerusholayim.
Israel’s enemies of yore would launch clear, all out war, on recognized boundaries. They were also not as motivated as the Palestinians would be. This would lead to a clear military response, which as a developed, advanced and heavily aided military (certainly in the past), Israel stood a good chance and repeatedly, besityata di’shmaya, won.
But a future Palestinian State would have two fronts, and would be incredibly well placed to further their current ramshackle terror campaign into a much larger, much better funded ISIS style terror campaign. This would not constitute an existential threat against Israel, rather just make life unbearable for it’s inhabitants. With a large sympathetic Arab population in Israel, they would be able to launch mass casualty guerrilla raids, widespread rocket fire, and dig tunnels literally all over Israel, turning Israel into something nearer to Vietnam.
And this campaign would, as we have seen in Gaza, be virtually impossible to effectively combat. As a state, Palestine would form allies with surrounding Arab nations, which would be far friendlier neighbours than Egypt has been to Gaza. This would mean any overt war could turn into a simultaneous fight from both within and without, the like of which Israel has never faced before.
I agree it’s a bit of a doomsday scenario, and i’m sure the defensive measures could stop avert many of these dangers, but the facts of the matter are clear. Israel can’t, and hopefully won’t, even begin to consider handing a mortal enemy the launching pad, both literally and figuratively, to attack it.