Well, their coalition agreement already actually contains the stated intent to annex the West Bank. The specific wording reads:
“In light of our belief in the aforementioned right, the prime minister will lead the formulation and advancement of policies within the framework of applying sovereignty in Judea and Samaria [Judea and Samaria is their ideological wording for the West Bank]” Source: https://www.timesofisrael.com/netanyahu-far-right-ally-said-to-agree-government-will-advance-w-bank-annexation/
In that sense, you can essentially assumed that the probability is 100% - as it always is for things that have already ocurred!
There is, literally, zero chance that this particular Israeli government - yes, even with the broader "war cabinet" coalition they have at present - will NOT generally support annexation and ethnic cleansing. And while Netanyahu himself is not a messianic settler extremist, make no mistake: his entire political legacy has been to undermine any hope for any two-state-solution. That is, literally, his political legacy. Also, incidentally, why he was quite keen on bolstering Hamas - he thought it would undermine the PA and avoid any threat of Palestinian unity (he was right about that - it worked!).
The question is not: do they think this? The question is: will they get away with it?