Remake SR2!
But more seriously....it depends on what direction they want the series to go in - SR3 kinda doubled down on the whacky/zany aspect the series touched upon in 2...and then 4 doubled down even further - and in both instances, the game lost at least some level of 'depth' as it got more shallow to allow for more zany hijinx.
So unless they keep wanting to ante up and increase the whackiness factor (which is going to eventually get tough to do, not to mention the underlying conflict with the 'game' systems and the problem of the player getting blatantly overpowered), they probably need to strike a better balance in whackiness versus grounded/realism for the narrative.
But honestly, I'm kinda hoping for some other aspects that really made SR2 cool - a lot of fleshed out world space, hidden secrets galore, etc....but a part of me realizes that costs a lot of money, for not a lot of tangible 'return'.
SR3 was still decent at being its 'own' thing before SR4 jumped the shark (even if Steelport SUUUUUCKED compared to Stillwater), so maybe combine that 'differentiation' but include some of the deeper aspects SR2 utilized, I guess?