Me and 42 of my buddies "say" (granted some of us might be "lying") we wont' buy it if it requires Steam like FONV did. Check my sig for the links to the survey and the responses. Apart from that, I can think of nothing that would stop me from buying and playing it!
What If Skyrim is Steam exclusive? Will you buy it?
I will buy Skyrim whether it requires Steam or not. 41.2% 49
I would prefer if there are non-Steam options for authenticating and playing Skyrim (e.g., gamesas online store with a unique product CD key). But I will probably buy it if it requires Steam anyway. 22.7% 27
I will not buy Skyrim if it requires installation of the Steam Client and internet connection for Steam authentication. 36.1% 43
answered question 119
skipped question 7
There were also two previous polls on here that maxed out in length which indicated similar patterns.
http://www.gamesas.com/index.php?/topic/1155984-skyrim-steam-and-you/page__st__180__p__17019871__fromsearch__1#entry17019871
http://www.gamesas.com/index.php?/topic/1158809-what-if-skyrim-is-steam-exclusive/page__st__200