It's going to be a rough ride; at least the coming winter for sure. But I'm very optimistic about the long term effects. In fact, I see this as setting Europe up for a period of economic growth. Getting rid of fossil fuels decades ahead of schedule is going to involve a lot of public spending and there is going to be a massive return on investment. Big public spending is generally great for economies. Once that starts working, there are going to be a lot of other countries that will want in on the action. Countries investing massively in serving that need are going to do well in the next decades.
Germany, which hasn't done much public spending in decades has just unlocked hundreds of billions for investment in military and energy. Other countries are doing similar things. That started happening within weeks of the invasion and it's just the beginning. This will soon add up to trillions in spending.
And of course there is the notion that Russia might eventually decide that they want to sell some gas again after all. Gas prices are high currently and that compensates for the loss in export volume for them. But those prices are inevitably going to come down eventually as other energy sources become more available and the world adjusts. Russia seems to have no good plan economically other than selling gas to Europe. This winter is going to suck a lot harder for them than for anyone else (well except for Ukraine) and it's debatable if their exports will ever recover to the pre-war level.