In it's state now, I don't think that bards can be considered support class. But I do suspect, that when the release a true support class (probably in the next major expansion) that the role of bard might change. Of course, archer will have a more dps orientated class like ranger. (Actually, would it not be cool that musketeer and archer both end up Ranger as a job option - so you pretty much keep your class skills - but gain 5 Ranger skills)

However, I do think that how support (since they will still bring their own DPS to the table) functions is that their skills buff the rest of the 3 members to make up for the difference in DPS.

Say for example, a support class deals 80% the damage of a true dps class. between, the tank, the healer and the DPS. A support class would be required to add another 20% DPS. Of course, the overall capabilities of a party is not restricted to damage dealing, as such, a support class could also buff the party in other ways.