This is an interesting point. One can go for a complete revamp of the MKI's airframe and avionics in the first set of upgrades, including a GaN radar. These can be detuned for a lower power output as of now to work with the Al-31 engine. By 2025 once our economy is in much better shape we can see if the item 30 engine works for us in the MKI. If it does then it won't be a bad idea to pay for an engine upgrade. In that way the MKI upgrade can be broken into 2 phases:Al 41 is just an improved version with a new name so that they can charge more money for license fees.
Why pay for AL 41 then better wait for the new su 57 engine IZ 30 derivative.
IZ 30 have 100+ kn dry thrust and will be suitable for next 25-30 yrs demand.
1> Phase 1: Airframe overhaul, new avionics from LCA Mk2 and AMCA programs, with progressive blocks of improvements year after year.
2> Phase 2: Engine upgrade.
Note that all avionics won't be ready so soon. So if MKI upgrade starts next year, then we can at least expect for the first block (the oldest MKIs) to get their airframes overhauled, and all existing Indian tech to be fitted in, along with whatever foreign kit that needs to go. The next block can have scaled up Uttam GaAs radar and LAD, the one after that can have AMCA type GaN radar and deep sensor fusion, etc etc.