Well, I'm excited. If for no other reason I'll be curious about the direction they take it. This doesn't mean I'll have my heart set on it fulfilling my own personal ideal Thief sequel.
It won't match the original because it can't, and that's okay. I really don't mind replaying the original or the many fantastic fan missions for TG or TMA when I crave that taste of authenticity.
Maybe I'm a bit of an optimist, but I think Briareos H made a couple important points:
1) The development of Deadly Shadows suffered from exceptional technology constraints and developer drama. I'm sure Eidos understands this quite well and will make a real effort to not repeat those problems. Stephane D'Astous' initial comments about the creation of the Eidos Montreal studio and around the announcement of Deus Ex 3 indicated that Eidos really wants to give this new development studio all the resources it needs to get things right.
2) Like Briareos H, I really do believe publishers are experiencing a bit of a backlash from "streamlining" popular franchises. I think this could bode well for the next Thief. I'm not saying it certainly will bode well, I'm just saying it could.
I also seriously doubt they will modernize Thief. This fear derives from some random, out-of-touch executive speaking broadly and vaguely about different Eidos intellectual properties not long before he lost his job. We don't have any reason to believe those comments were anything more than some random man's personal and random ideas on the publisher's future.
Thief's iconic setting is a vital part of its identity and I'm confident the people that matter in its development appreciate it.