Well tbh this doesnt sound like a bad idea, but making them a tml projectile doesnt realy make any difference when you want to snipe a pushing acu (they wont have tmd).
When it comes to sniping somebody sitting in a base i think this would be a massive buff to mercys since nobody really has more than 2 tmds sitting in one place to defend vs 15 tml rockets and 1 or 2 aa wouldnt be able to to kill a mojority of the mercys, sice they have way more hp now.
I think if you remove the homig missile part this would actually make more sense.