I think the changes to
are a step towards improving AD caster itemization overall, even if cooldown-dependent assassins like
are going to have a slightly harder time. AD caster itemization is way too dependent on
overall for its early/mid-game power spike, and weaning champions off of it would allow for smoother and more diverse build paths (we could end up with a cheaper AD + CDR item, for example, which so far has yet to appear). The flipside to the loss of early burst on TBC is that it will allow AD casters to scale far better into the late game, especially since the additional CDR means it'll be a lot easier to max out on the stat.
On the other hand, I also think Panth would scale a lot better with
if attack speed were genuinely good on him: his passive already encourages it, and there are a lot of ways the stat could be made more attractive on him, yet right now he is completely dependent on the current state of AD caster itemization, especially the mid-game burst it provides via CDR and flat pen, to do well. There's a lot on his kit that looks like it needs updating (his main nuke and his hard CC are both point-and-click, which forces him to have terrible mana management in lane), and hopefully the tweaks he'll receive will allow him to be more versatile in what he can choose to build.