At least among the online audience, Conduit seems to have a stronger buzz than Punch-Out. The people who bought Punch-Out were mainly the folks with Wiis who had owned the NES game or, to a lesser extent, Super Punch-Out back in the day.
Interest in Punch-Out has really dropped off already among core gamers due to the lack of boxers and the difficulty curve on Title Defense. Nintendo's ad campaign, although great, really only targeted the 2-3 million people who had owned the NES game. The sport of boxing has tanked since the NES game was released as well. If I'm a casual gamer, I can already box the computer and other people with Wii Sports.
There is quite a sizable fanbase for the Conduit game that will be playing it for months online and spreading buzz. A lot still depends on what Sega's TV ad campaign is and how the rest of the reviews are, but I'm still confident it'll do pretty well.