Others mentioned AZ and TX, but I think FL and PA also deserve to be mentioned. Both are large states that straddle different regions (FL doing so in a unique way), and each could go in different directions depending on the exact composition of the parties going forward.
I agree on Pennsylvania, especially if the Rust/Sun Realignment is really a thing (and it is).
Saying no President will win without GA doesn't imply that there won't be other states that every victorious President wins. Florida and Ohio have been perfect since 1996 (and Ohio has been perfect since 1964).
If the Democrat wins in a very close race in 2020, there's a decent chance of them winning without Florida, though.