Why does India maintain an N-triad at high cost to the exchequer? Because redundancy is key for deterrence. The Jag and M-2000 are well past their prime. There's no reason why the MKI can't take on the role when its contemporaries like the F-15 (based in the UK, Germany and elsewhere) are a key part of NATOs nuclear insurance against Russia. MKI certainly has the range, payload and endurance for such a mission+ lt's a two-seater. There are no treaties between us and our rivals that require us to disclose which IAF assets are nuke-capable so there's no point in making it public.
MKI does not have the EMC rating necessary. To get that, it will have to be upgraded from scratch, like MLU. But the IAF is not gonna give up the MLU jets to the SFC.
M2000 and Jag were recently upgraded, so will remain relevant for the next 15-20 years. As long as the jet has a modern EW suite, comm, and nav, it's enough. An SFC jet is not going to get into fights, so it doesn't need all those modern avionics. The main criterias to be met are reliability and survivability.
Furthermore, SFC can demand jets as necessary. And they won't just ask for 1 or 2 jets, they ask for multiple squadrons. Taking away 1 or 2 squadrons of their most important jet will drill holes in the IAF's operational capabilities. And more jets will have to be given up for escorting those jets. So the IAF is not dumb enough to give up their most advanced jet meant for air superiority.
The same with the USAF. You speak of the F-15, but it's the variant that matters more. Neither the F-15A/C nor the F-22 are nuke certified, only the F-15E, F-35A, and F-16 are. In fact, they were so focused on the air superiority mission that the F-15A/Cs made the quip "not a pound for air to ground" famous. The F-22 too has small IWBs because its strike capabilities were added due to the proliferation of the S-300, and some DEAD capability was necessary to fulfill its AS mission. So neither jet will be given up for the nuke mission, the same as the MKI and AMCA.
So majority Jags for now, with some M2000s. In the future, let's see. We will be rich enough for the SFC to have their own type. With our nuclear stockpiles increasing on a yearly basis, the SFC will eventually need 2+ squadrons of their own.