One interesting thing with vehicle to grid is that EV battery capacity is becoming a valuable commodity. It's valuable to EV owners because they can sell back electricity to the grid and manage when they charge using either solar or simply low rate night time energy from the grid. This saves them cost and some cases makes a profit. It's valuable to grid owners because they can serve peak demand from plugged in EVs and dump access clean energy back into them so they can stay on top of peaks in demand and supply. It's even attractive to battery leasing companies or EV car companies responsible for managing the batteries because keeping them fully charged all the time when they are not in use is actually not that great for battery life. Some car manufacturers are already experimenting with battery warranty and vehicle to grid usage in order to take away the concerns about wearing out the battery.
So, vehicle to grid may be used to address exactly this issue. It's a complicated topic of course but providing charging points to garage orphans could be a profitable business. There are all sorts of interesting things happening around this.
Swapping batteries is of course covered by existing warranties and obviously this is already technically doable as part of normal car service. So, no special new design is needed for this. I imagine this typically involves unplugging a bunch of cables, loosening a few bolts, etc. Doesn't sound like rocket science. In any case, your base assumption that this becomes a regular thing for EV owners is probably simply wrong. It's rare now and it will probably not become a lot more common. EV batteries are pretty good.