Well, DH Smith is a Hart, just has his father's last name as opposed to his mothers. That's the thing people always tend to forget with him because he's Davey Boy, when in reality, he's also the off spring of a Hart Sister. Like wise with Natalya. Natalya is Neidhart's daughter, but alsot he daughter of another Hart sister. Just because they ahve the last names of Smith and Neidhart as opposed to their mother's maiden names doesn't make this any less of a Hart Foundation then the previous incarnation.
The Hart's are coming, and I personally like it. These kids are third generation stars, and have been around the business their entire careers. The only thing they lack is an older Hart to give them instant credibility, but give them time and they will get over on their own merits.
I said it months ago, if Legacy begins a good run that last several years, look for the Harts a couple years down the line to have a run in with them, which would be awesome.