Given the impetus and if there is a degree of ruthless pragmatism and intent to completely eradicate both sides as effective organizations by the UK, then with that background they could pretty much gut the structures comprehensively of both sides at the same time.
Part of the problem though is that there was a fairly direct institutional bias in the leadership of Operation Banner towards the violence committed by the UDA/UVF/loyalist paramilitaries. Especially early on in the conflict. Their actions were seen as a purely defensive reaction to the alleged inauguration of violence in the six counties by violent Republican ideologues. On the ground, the Ulster Defense Regiment played a support role to the army and it has been pretty well proven now that soldiers of that regiment were active simultaneously in loyalist paramilitaries. There’s fairly well documented though disputed evidence of British army and intelligence collusion with armed loyalism as well - generally considered to be part and parcel of Frank Kitson’s counterinsurgency strategy.
With a Provo attack on the Queen, I think these institutional flaws are going to be exacerbated rather than minimized. A British army going outside the law to fully crush Republican paramilitaries is going to almost necessarily need to use loyalist paramilitaries to supplement their efforts… Lists of prominent PIRA/Sinn Fein targets ‘go missing’ when the Army can’t conveniently justify their detention or death. This then, of course, triggers a sectarian Catholic counterreaction as they see the supposedly neutral army acting no better than the hated B-Specials and the return of army occupations of the Bogside, Ballymurphy, etc are going to trigger another mass counter reaction like they did in the early 70s which heightens the untenability of normal governance and once again puts the British on the back foot in terms of the international spotlight (I’m also going to assume that putting scared young men with guns in the middle of rioting hostile communities again is going to lead to at least another massacre).
I think it’s also worth mentioning that the point about destroying the leadership is well taken, but it also must be acknowledged that a significant cohort of Republican leadership came pretty directly out of involvement in the early 1970s. Men like Gerry Adams or Bobby Sands were created by the conflict rather than being some trained reserve coming in from before the Troubles began. I do believe that it would take less than you might think for another Army fiasco in West Belfast to produce another ad-hoc generation of leaders and junior officers in the Republican paramilitaries unless you reintroduce some far more sweeping internment which produces another *massive can of worms*. Groups like the UDA pretty much produced their entire structure through grassroots leaders and though it did produce a lot of structural issues in their organization, they could keep in the fight and I think the same applies to republican paramilitaries
A multi-pronged approach against all paramilitaries could potentially be a good solution, but historically that wasn’t how those institutions were thinking and working in this time frame and now we are giving those same people more of a reason to be harsh and brutal rather than precise and exact. I’m thinking, at best, this offensive goes down in another costly stalemate or, at worst, is a pyrrhic victory for republicanism.