If the Switch 2 will have any form of BC, knowing Nintendo it will be only with digital games (not physical), because they love to sell you their games at full price.. By some miracle, if the cartridge port in the Switch 2 is the same (or uses the same technology?) as the one in the Switch, they could still charge you to use that feature *somehow* with some BS lock/ drm feature, specially for the ones when you have to DL the game data from their servers.. Of course i could be totally wrong here, just my 2 cents.