I don't think anyone is asking for just a straight upgrade to the old raid gear. The easiest way Bungie could probably do it while still retaining the "grind" would be just adding an additional level scale option for all the old raids once a new one comes out that places them all potentially at the same level, requiring Guardians to re-obtain the gear at the newly scaled level and requiring them to upgrade it once again. I say "easiest" because I'd prefer to see something like exotic bounties that involve playing through the rescaled raids with additional challenges, rewarding a token or something that would enable one to upgrade the gear without resetting the perks.