Lithium batteries have been banned from checked luggage for ages on the flights I use. But apparently that wasn't across the board. Some airlines are still catching up.
Using them onboard is also banned on lots of flights now. Because they still catch fire in the cabin. The restrictions exist for a reason and that reason hasn't gone away.
So they'll tighten certification. Make them pass more tests, meet higher standards. But it only takes one certified battery causing a cabin fire and I reckon they'll ban them entirely. The risk calculation changes fast when it happens on a plane at 35,000 feet.
That leads to two things. First, a big increase in battery rental — you don't bring your own, you rent one at the gate or on board, same model they use for wheelchair assistance and oxygen. Second, a massive push for solid state battery tech to become scalable. The airline industry has the volume and the safety motivation to force that market open.
Same pattern as always. Regulation lags, incident happens, regulation overcorrects, the market finds a workaround that becomes the new standard.