Against the view on the left that de jure, as opposed to de facto, annexation will only reveal the true mask of the regime and won’t make a difference in terms of direct legal-jurisdictional and social impacts on Palestinian lives in the West Bank,

Michael Sfard writes here.

Annexation will necessarily lead to the massive expropriation, automatic in some cases, of Palestinian land and property, the subsequent expulsion of individuals, families and entire communities from the annexed territories and a dramatic rise in the power of the settlers’ local governments, which today are a weak administrative entity that is controlled by the Israel Defense Forces.

On the illegality of annexation,

Nathaniel Berman writes here and here

The [From the Left] indifference towards, or even embrace of, formal annexation presents itself as a savvy, worldly-wise position, accepting the reality of the “one-state condition” and seeking to move toward a more just future. But the forces mounted against such a just future are enormous: ideological as well as military, regional as well as international. Our time does not seem one in which an appeal to universal sentiments of equality and democracy are likely to succeed. Nor does it seem an auspicious time for two peoples, who have fought so long to establish States identified with their ethno-national character, to give them up in the name of non-partisan universal ideals. Their resistance might be based both on principle (the ideal of national self-determination) and on pragmatics (a prudent evaluation of the chances for securing universal equality in an ethnically embittered society). In the face of these current realities, contributing to the de-legitimation of international legal prohibitions on annexation of territory acquired by force seems like an unwise wager – whatever the benefit of jolting the complacency of liberal bien-pensants.

Lastly, what happens if the annexation gambit flops. Is it back to same old same old or will that failure crack open new political horizons?

Without knowing for sure, about this Sfard can only contemplate about the messsianic imagination once thwarted:

This analysis ignores the political backlash that averting annexation would ignite. The right has been insanely lucky during the recent few years: Trump became president of the United States, Europe has been weakened by Brexit and other crises, the criminal cases against Netanyahu changed his political calculations and the coronavirus pandemic diverted public attention a moment before Israel initiated a unilateral tectonic shift. All of the stars aligned for the pro-annexation camp, and what appeared to be imaginary just a moment ago suddenly became realistic. Now imagine if the annexation were to be thwarted. For right-wingers, it would be as if the Messiah came and knocked on their door but they were unable to open it. How long would it take for such a perfect constellation to appear once again?

If annexation doesn’t happen within the next few months, it could very well disappear from the agenda for years, becoming irrelevant. The day after annexation is stopped, the occupation will be the same bad old occupation that must be fought, but the political situation will be new. As with every change, it could open the door to new opportunities.

More here by Dahlia Scheindlin with multiple links relating to the illegality in international law against states acquiring territories through war, even in non-state territories.