Tintin seemed to like his motorbike. Wonder if he would upgrade to a Harley. :D
I don't think Harley suites his active nature and mobility, since it is quite a big bike, and not so maneuverable. I think I prefer him upgrading to BMW motorcycles (or Ducati can be another option, of course :D).
Well, for tintin's pants, I believe it's the skinny jeans
I can't picture Tintin wearing skinny jeans though, I prefer him wearing normal jeans (which are not too tight on his legs XD). I wonder which color of the sneaker will suit him, maybe red or brown, I think it depends on his clothes color scheme.
And I definitely agree that he'll own a laptop and a cellphone, and I just have imagined that his cellphone is iPhone, which might give a hint to this question :
Oh, here's a good question: What would they all prefer? Mac, Windows, or Linux?
Tintin might prefer Mac, if he indeed use an iPhone (although he doesn't really need Mac for its iTunes, he can use Windows and download iTunes for Windows). Calculus in another hand, might enjoy using Linux (remember that Linux is open sourced so that anybody can tweak its system freely). Calculus might enjoy developing a new distro for Linux :D. As for Haddock, I have a nagging feeling that he uses Windows XP, and it suits him XD.
Anyway, I think that Tintin will definitely travel a lot more often, and he'll travel more with airplanes (hopefully Snowy can be still easily accompany him, since bringing animals in travel today is a trickier business compared in the 30s to 70s). He might be able to do some hacking, perhaps he'll do this in his adventures in 21st century, when he need to tackle his enemies in a building with an integrated computer system (he'll hack the computer system for tricking his enemies, like locking his enemies in a room or vault, closing doors so his enemies would stuck while chasing him and so on).