A week from today are the last Presidential primary contests of 2008. The remaining calendar:
May 31: Committee meeting to consider proposals to seat a delegation from FL and MI
June 1: Puerto Rico Democratic Party Primary (55 pledged delegates)
June 3: Democratic primaries in Montana (16) and South Dakota (15)
Obama currently needs 49 delegates to secure a 2025 delegate majority; Clinton needs 246 delegates (subject to the committee determination on May 31 and possibly a last minute change of policy at the credentials committee at the Democratic National Convention in August in Denver). There are 86 pledged and 201 superdelegates who have not yet declared their allegiances in the race.
Clinton is favored in Puerto Rico, but by a much thinner majority than in Clinton strongholds like West Virginia, Kentucky and Arkansas. Obama is favored to win substantially more than a majority in Montana and South Dakota. Realistically, Obama can expect to win about 42 more pledged delegates in the next week. Obama has also received a steady trickle of superdelegate endorsements and is likely to secure at least seven more in the next week. Thus, he will probably have enough pledged delegates and committed superdelegates to win the nomination by June 3, barring a change in the rules regarding Florida and Michigan.
The national party has refused so far to agree to any deal on Florida or Michigan that does not have the support of both the Clinton and the Obama campaigns, and also the suppport of the state party in question. Thus, delegations from these states are unlikely to be seated unless they are irrelevant to the outcome of the Presidential nomination race. Even if those delegations were seated at this point, Clinton would still lag in pledged delegates and would need to secure a disproportionate share of the remaining superdelegates.
Superdelegates can change their minds at any time prior to the national convention, but the more likely scenario is that superdelegates will flock to a presumptive winner, rather than jumping ship en masse from the Obama campaign to the Clinton campaign.