Yes it still possible, there's couple members that already got full member or even senior member from low rank. Try surf this meta section and find thread about people that already rank up. One that i know is
DdmrDdmr who already earn more than 1k merit and he can wait until the time come to make him become legendary and looks like he start from newbie or jr.member(?).
That person has done exceptionally well. Good spotting, i just looked through that users profile a little bit and the user is very active i see. So this proves it is possible but i think it is a rare circumstance seeing people like that and i would be willing to state that there are probably less than a handful of users that are able to do this. As a community based forum don't you think the opportunity should be much more widespread rather than just a few users out of thousands able to gain rank? Interesting that some are able to do this still though, thanks for the information.