With Trump warming up to Pak once again, we can only buy leverage via oil and defence deals, imo. (these two aspects were specifically mentioned during Modi's visit to DC earlier). After Howard Lutnik's recent outburst that India was "rubbing America the wrong way" by buying Russian arms, we've got to play our cards well. Ultimately, those guys are the ones advising DT on foriegn policy.
If we dangle the F-35 purchase carrot, we may be able to stall the sale of F-16V B70+ AMRAAM C7 to Pak which seems to be very likely atm. Whether we ultimately buy F-35 or not would depend on the progress of Mk2 and AMCA. Try and buy ourselves some time until we decide on the best path.
As for a Su-57 JV, too early to tell.