You are right, and the explanation is simple. Pro Tools 11 is a 64 bit application, which does not support RTAS plugins. The new format is 64 bit AAX, which basically isn't available from the plugin manufacturers yet. AFAIK Line 6 hasn't mentioned anything about a possible AAX update since october 2011, when this was written:
"I'm pretty sure that when that standard is implemented we will also move towards making our software compatible with that format to stay relevant. There is no public info on when this will happen, so stay tuned to the website."
So, it may or may not be coming, since no info is actually known about it. As of now though, you cannot use POD Farm with PT11.