State of gaming on linux?

I used linux in the past, both privately and work-related, but the last time was over 10 years ago, so I'm a bit out of touch. I am in need of a new PC, but it'll be a good year before I have the funds, so for now I am making due with an i5 7500 and a gtx 1660. I do have 32 GB so there's that. I finally feel confident enough to make the permanent switch to linux from windows as all of the programs I use are either available on linux or have a good/better equivalent. The only thing I fear will hold me back is games. I know Steam has Proton now which will run most games, but how does it compare? The games I play most are Skyrim (heavily modded) , RDR2, Witcher 3, Transport fever, Civilization, Crusader kings 3 and Cities Skylines (uninstalled atm waiting for 2). I'm on the fence to either wait until I can afford a new PC and dual boot or make the switch now and deal with a few gaming problems. Thing is, what kind of problems may I expect? Anyone able and knowledgeable to give me some advice?

EDIT: Wow, those are a lot of replies; thank you everyone! You really helped me. I will make the switch sooner rather than later.