We can bring it's clean rcs under <2m2 for most of frontal arc, which will provide significant benifits.
A rafale loaded with missiles and drop tanks has rcs >2m2( oh yeah rafale doesn't have much low rcs geometric features unlike how the French hype it up, but ram is there).
Su30 wouldn't need drop tanks.
A jet loaded with missiles with similar rcs as loaded rafales( with missiles and drop tanks), but highly powerful avionics.
Supersukhoi would surpass rafale as a bvr fighter, if actual work on rcs reduction is done as part of super sukhoi deal.
Actually there were some indications in old news on reduction of su30 rcs to some extend for delayed detection . I am refering to news of a kind of RAM paint developed by Jodhpur laboratory which was in news . I can't say it ll be done or not . As far as radar capacity is concerned upgraded su30 with gan aesa with 2600 tr modules ll far surpass any fighterjets IAF got . With astra mk2 bvr missile and astra mk3 awacs killer , brahmosh ng it ll impose significant threat .