The most that FE10 does at the moment, near as I can tell, is cause some minor interp splits for some characters. By this I mean some people might just vote on the FE10 form despite only FE9 being ranked. This wouldn't be the first game to be like that.
Xenosagas, Lufia Sinistrals (and possibly Maxim and Co. from Lufia 2, though both games are ranked, so this is more a past issue), Pokemon to some extent are examples of games with those current issues that are not only ranked, but STILL have those claims.
Some games from the past use to have those issues. While it was short lasting, Valkyrie Profile comes to mind, and it even CAME UP since I know some people voted on Hrist's VP2 form when she was still in Light before VP2 got ranked (though, the argument there was "She got a legit form in a later game, and that form is clearly a plot one, so its a really weird case" and not the norm but...yeah)...only example I can think of offhand, but the point stands.
Its true that FE10 has some changes for dueling forms (Elincia gets much better, Ike's got a more tank build instead of balanced, etc.), but...again, we have games ranked like that already, and those games get along fine, and FE10's changes are less drastic than, say, what Lufia 3 does to Erim, or what Xenosaga 3 does to Jin.
As shown by the FE9 ranking topic, most people are willing to not even consider people who have ranking worth based solely on FE10 (Sothe is a perfect example; useless filler PC in FE9, one of the main characters in FE10), and just wait til that game gets ranked, and rank based off that.
When/if FE10 gets ranked is a totally different story altogether, and as super said, the game's nowhere near ready. Probably won't be ready anytime in the near future either; if it ever gets ranked (keyword: if), by the time it does, we'll probably have had at least one more freeze and a few ranking sessions before that, and...yeah, point is, not a game that's going to get much pushing.
Proof?
Pokemon Diamond/Pearl. Game that is much stronger than FE10 at the moment, and is also a follow up from other games that are ranked...but no one has pushed for this idea. Granted, maybe cause they want to avoid Pokemon arguments, but the fact remains, the idea hasn't been pushed. What's to say FE10 is going to get pushed as soon as FE9 gets ranked, if a game that's got a much stronger case (in terms of playership, etc.) is getting next to none?