We'll need to wait to see how valuable the Inspire keyword is before we can assess this one fully.
Ah, you mean in case we have any Undertaker-like cards which specifically call out the Inspire keyword? I'm kinda skeptical that there'll be enough of that to make a big difference... the Inspires we've seen so far have already had a pretty large variety of effects, and it'd be kinda weird to call that word out specifically when the cards which have it don't necessarily have much else in common. It's the same reason we don't have any cards specifically about Battlecries, except for Nerub'ar Weblord, which is generally considered a pretty weird and dumb card.
As for Coliseum Manager (the new 2/5) specifically... I doubt it'll ever be used in Constructed, except in some sort of Warsong Commander + new Inspire shenanigan combo deck, but I think it'll be better in Arena than people are giving it credit for. 2/5 is a solid body on turn 3, and the ability to heal it up and along with a free hero power for 5 mana and 0 net cards is kinda comparable to Azure Drake or a super-Gnomish Inventor, if you squint at it. I don't think it'll be a
good card, though, because being unable to use your hero power without a big tempo loss is a problem.