This is correct. Listening to my little cousin who got a 360 this christmas, word on the playground is that the Wii's 'old and boring' now and he's 'grown up so needs a proper console', this coming from a kid who's got a Wii, DS, 3DS, and Tablet. Ive no doubt he'd of been happy with a PS3 but from a parents point of view a 360 looked like the best option.
Purely anecdotal of course, but the Xbox 360 has easily been this year's most popular gift among my son's friends (who are all 9 or 10). As the Wii has faded out, the other consoles seem to be making more inroads into the kid market as they fall in price. None of those kids had them before, so although you might not be selling to new hardcore gamers, that doesn't mean you're not still reaching new people.
That aside,, I can't see many new sales of Xbox or ps3 being made as first time purchases.