No, Brutes are not obsolete. They are on the whole sturdier than Scrappers/Stalkers and generally deal more damage than Tankers. Yes, there are exceptions to that on either side and depending on circumstance, but there are places where Brutes do better in the overlap realm too.
As to being needed, no AT is. I did Tanker Tuesday last night where there were only Tankers teamed together. I have done all ranged groups, even all Blaster groups and it turns out no individual AT is necessary for a group to do well. So do not worry about your Brute's contribution, the Brute is contributing in a way that only Brutes can.