Token standards can only hold so many balances and/or Tx's? Possible exploit?

As I’ve been researching token standards, it seems like the big names Dip20, is20, etc. have their transactions and or balances stored on a single canister.
I haven’t done the precise math but by my estimates of the bytes in a hash of a principal it seems there’s under a billion balances till the canister freezes at 4gb.

I know the icrc is attempting to do some kind of scalability thing similar to the Icp ledger for infinite transactions but at the immediate term, has anyone found a a hole in my concern?
And curious to know what kind of solutions people have created If so?