Here's an idea (regarding armor upgrades) (Destiny)

by stabbim , Des Moines, IA, USA, Wednesday, February 04, 2015, 18:25 (3377 days ago) @ CyberKN

I think the gist of the proposal is that you can use any piece of legendary armour to hit max level. Raid-themed armour still drops, and has perks that make it beneficial to use during raids, but its default stats aren't superior to other armour.

This bit right here is the part to focus on. The specifics of which type of shards are needed at which stage don't really affect the overall proposal much.

TBH, this idea of being able to upgrade any legendary armor to raid armor light levels seems so obvious now that Cruel's said it, that I wonder why this isn't just the way the game is already. Maybe when the next expansion rolls around.