What I'd really like to see is some for Hecarim to get some sort of sustained movement speed boost. In his current kit, his passive only seems to kick in meaningfully when you're doing a gimmicky homeguard teleport or when you use your E.
An option like the one you listed would work, although I feel like that gives mixed signals about what to build. I'd prefer an option like skarner, where Q gives a stacking movespeed bonus. Seems better both mechanically and thematically (can't run from death/being ridden down by cavalry).
Also, I'd like to see him back in the jungle. Maybe instead of changing his W, Riot should have just removed the monster damage reduction in his Q.