sounds like there is
http://www.neogaf.com/forum/showpost.php?p=125667041&postcount=231
https://www.youtube.com/watch?v=IVpbkwBbY4M&feature=player_detailpage#t=2173
Seems to confirm that there'll be a storyline and rival characters, at least to some extent (and that events will still be gated by wristbands).
Although it's definitely somewhat different to the original. The forzamotorsport.net writeup has some details about how it's going to work:
There is according to the 20 minute gamescom video with Ralph Fulton I saw a few days ago. Will take his word for it.
Remember reading an article from about a month or so ago saying there wasn't a story. My mistake then -- would prefer if there wasn't one TBH.