Europe also gets gas from the North Sea countries Norway/UK/Netherlands, also Algeria and Libya. It can also import from US and Middle East via ship. Russia is a critical supplier but it isn't everything.
I agree. But cutting imports from Russia quickly will be a major task. Is the US going to support the EU with subsidized energy to help with the transformation?
Shares of EU imports as of 2019 from Russia where as follows:
Coal: 46.7 %
Gas: 41.1 %
Crude oil: 26.9 %
(Note: These figures are shares of imports, i.e. they do not consider domestic EU production.)
EDIT: Maybe I should add a bit of context: Even if Gas can be filled in from other sources there are limits and the price will hike quite a bit even if there is enough. Furthermore it's unlikely that Russia will take it lying down, cyber attacks on infrastructure for deviling Gas are to be expected and maybe even physical sabotage. At the same time to safe money many Countries have kept increasingly smaller Gas reserves in recent years.