No plans for a larger tank. I've spent 3 years buying equipment (and replacing equipment) for my 350. I've lost two MP40s, two SKimz S18s, and two 300 watt heaters in the last three years. I can barely keep up with the cost of replacing dying equipment. To their credit they were old equipment (7-8 years old) housed in cold storage (below zero temps in the winter) for 2 years. So, unfortunately they did not weather well.
That said, I'm on my final stretch of equipping my mixed reef with the final circulation pumps, controller, and redoing the sump plumbing to make everything easier to maintain. That's my winter project. Once this is complete, I will be moving on to planning out a much smaller tank for my stay at home office. Probably a 45 gallon AIO nano or AIO converted to sump. I'm hoping for maybe a planted macro algae tank with sea horses or some other theme tank I haven't thought of yet. (Zoa and Acan garden? Not sure.)