First, a quick side note -- I don't think there was ever a mention of channel 10 doing a 10pm newscast. Though, if they ever got a secondary digital channel (like WHAM had with CW-WHAM), nothing's stopping them from making it happen.
Answering your question, right now, WHEC is airing back to back episodes of "Everybody Loves Raymond" at 7 and 7:30. Kind of odd, since sitcom reruns usually wind up on Fox, CW or MyTV affiliates. Then again, I don't know what WHEC had in these slots before the current TV season started. If they were carrying something more along the lines of Insider, Access H'Wood, ET, Millionaire, etc. (stuff that's more "typical" for a big-3 affiliate in the 7pm hour), they probably dropped it this fall, knowing they'd be launching a 10pm show. I assume the contract for reruns (which already made their money the first time around) is more flexible when it comes to dropping or moving the show mid-season, than it would be for a show that's producing new episodes every day.
It'll be interesting to see how well a 7pm newscast does, compared not only to the other 7pm programming, but also compared to the 5/5:30/6 newscasts. If WHEC is only willing to dip its toes in the water to see how cold it is, they probably won't do so well. But if they're determined and committed enough to run up to the pool and do a cannonball into the water... it could work well. That is, assuming people aren't "newsed out" by the time 7:00 rolls around.
Again, in the NYC market, you have the demographic of people in the suburbs who are just getting home from work at 7. They haven't seen ANY evening news yet. Rochesterarians (?) who might only have a 20-30 minute commute could get out of work at 5 and still be home in time to turn on the TV by 5:30. After seeing a full hour of local news and 30 minutes of network, do you really want to sit through another 30 (or 60?) minutes of local news?
Sure, you have the folks who might go to the supermarket after work... or run errands, chauffeur the kids around, and so forth. They might not be getting back home until 7. But are there really enough people on that schedule every single day to make a 7pm newscast worth it? I'd certainly be interested to know what led WHEC to believe the answer to that question is yes.