The dealer supports re-calibrating for both tires and gears, and FCA openly talked about supporting it at launch.Except, I can throw my factory wheels and tires back on the Jeep in 15 minutes if I need to go in for service. Can't do that with a ring and pinion swap.
Monster tires, unbalanced tires or incorrectly installed gears would be an issue. Larger tires can often require regearing for proper operation.
I laugh at big tired 4x4s that cant go up hills, if you cant regear a wrangler its a total pos not worth buying. Thats clearly not what Wrangler designers are aiming for.