Someone with Nami (E) or Braum support, for one, though that's not directly the ADC. Vayne and Tristana both benefit from being able to get a large number of autos off in a short window.
Caitlyn could use the speed to get close enough for normal AAs after someone steps on a trap, or use the speed to get away after hitting an E on someone trying to gank her. Champs like Ashe, Sivir, and Lucian already increase their own speed or slow the enemy when attacking, and this would synergize with those effects. From the other side, Draven could use the speed boost like a free W (when he needs to compensate for slowing down to catch axes).
There's also more general use cases. If you're chasing someone with Rapid FireCannon, the speed boost could be enough to get you into normal auto range. If you're chasing someone with Phantom Dancer, the speed boost could be enough to get you into the additional movespeed range. If you're getting ganked and your support stuns the ganker, your speed boost from your auto should grant you more MS than you lose from the animation (unless you're like level 1 Jinx with rockets). It could help you dodge a skillshot that the enemy fires off as you're last hitting.
The lifesteal portion? Not really; that's just a straight and obvious nerf. But there are many ways to put the MS to use.