Useful article by Michael Herzog in Foreign Affairs explains why the idea that Hamas will be tamed by office is an illusion. Quite apart from the non-negotiable nature of its oft-stated and now firmly repeated position that it intends to destroy Israel, Herzog observes that the conditions under which other terrorist organisations have come in from the cold do not apply here:

The most important lesson to be drawn from these cases is that co-optation through political participation is not a given, but rather depends on the existence of certain conditions in the local political context. No Islamist movement has renounced violence or moderated its ideology of its own volition; when one has done so at all, it has been for lack of a better alternative. It appears that at least three factors need to be present for co-optation to occur: the existence of a strong, healthy, and relatively free political system into which the Islamists can be absorbed; a balance of power tilted against the Islamists that forces them to play by moderate rules; and sufficient time for co-optation to take effect…

Unfortunately, if one looks closely at the case of Hamas, hardly any of these potentially moderating factors are present. Elections in the PA may be relatively free. But Palestinian political, security, and other institutions are a chaotic mess, and the pragmatic political center, represented by Fatah, is in complete disarray. Hamas is launching its political career in the legislative and executive branches without having disarmed and is quite possibly stronger than the rest of the state apparatus…

The ongoing Palestinian-Israeli conflict, meanwhile, adds fuel to the fire of domestic Palestinian turmoil and to extremism. It provides an excuse for tolerating private armies within the PA and enhances the legitimacy of Hamas' rejectionist stance. Opinion polls show that although most Palestinians disagree with Hamas' ideological extremism and support a two-state solution to the conflict, they also accept the notion of "armed struggle" as a legitimate route to get there, citing the Israeli withdrawal from Gaza as an example of what such pressure can achieve. This complicated preference structure gives Hamas a perverse incentive to disrupt progress in diplomatic negotiations, since the normalization of Palestinian-Israeli relations could well lessen Hamas' appeal. As long as its military and political power enhance each other, Hamas will be able to fend off pressures to disarm and will derail progress toward peace. Given the urgency of moving the conflict toward resolution, finally, there simply is no time to let Palestinian domestic politics play out long enough for Hamas' political socialization to occur.

Quite so.