That's the best case scenario which is that EU has enough gas only for home users, so they'll have to shut down literary every industry they have that uses gas. The significant increase in price of wood, industries that shut down already and declared bankruptcy and some are on the brink of it, the temperature laws that some countries like Switzerland are going to start enforcing soon, etc. are all signs of severe gas shortage.
P.S. Worse case right now is if a new war breaks out in another region or two where Europe gets its energy from

Azerbaijan ships in large quantities of pipeline gas to the EU, and the pipeline goes through Georgia. And back in 2008, there was a conflict between Russia and Georgia. Since the current regime in Georgia is not very hostile to Russia, the chances are very low. But still I won't rule out the possibilities. Nigeria and the Maghreb countries (especially Algeria) are also important sources of gas to the EU, and these countries are politically very volatile. Only stable suppliers are United States, Qatar and Australia.