It all depends on his opponents. We already know his ego is HUGE and that winning [re-]election would prove once and for all his legitimacy for his tombstone and history books, should it be feasible. It all depends whether a black candidate declares and how many, uh, "candidates that can appeal downstate" declare.
Burris has a leverage but he needs to consolidate his base. I could see him winning if too many "candidates that can appeal downstate" opponents run against him in the primaries. Face it, the best Republican candidate[s?], like Kirk, will have to decide before they find out whether or not Burris wins or possibly whether or not Burris even decides to
run for [re-]election. Thus, the big question mark over whether the GOP will have to face someone like Schako, who will have an easy victory, or someone like Burris, who would not have an easy victory, is... well, a big question mark and could discourage the best GOP candidates against Burris.