I did multiple searches and only found others asking the same question. Has anyone tried or know if it is even possible to R&R the J-gate for a rotary?

I would think it would be difficult.

I have not looked at potential mechanical issues, but in my work on the Remote Top upgrade I learned that the CANbus protocol changed starting with the 2010 model year and both High speed and Medium speed CANbus networks interface with the shifter unit.

would be nearly impossible without changing the entire loom , and the gearbox is also different , cost would be excessive , why bother?
id have chosen to go the other way , rotary to stick

Don't care about cost, more concerned with feasibility. I am a slow adopter and have always preferred the J-gate but rotaries have been around for a few years now and kind of growing on me.

With the paddles, the only time I use the rotary is to go from P to R or D, or D to R, or back again. Long story short once I got used to the rotary the only thing I miss about the stick is resting my hand on it.

Very few things are impossible, but it would be a hell of a job, even if you could find someone with the knowledge to do it. A far easier and more cost-effective route would be to trade up to a 5.0.

I wouldn't. Stick is classic and functional. Knob is silly. Even the highly praised F type went back to the stick! Stick with the stick!