Eh, I like my chances so far.
I mean, whether it's DMC5 or DmC2, it's still the fifth game in the series. And it's not like there are dedicated websites for DMC1, 2, 3 or DmC, the games' pages are either under the devilmaycry.com URL (such as
http://www.devilmaycry.com/dmcde/) or under Capcom's page (like
http://www.capcom.co.jp/devil4se/). So, yeah, the registration of a website called devilmaycry5.com doesn't say much to me, and doesn't even line up with the leak (which mentions the game being called Devil May Cry V, not 5).
Edit: striked through something that's actually not true, since it'd be the sixth title counting 1 through 4 and adding DmC.