So, there is actually no mathematical limit to the number of coins. It's just that the issuance of coins is not subject to a central authority, but requires a supermajority consensus.
The mathematical limit is in the code. And that limit is the result of the halving. Maybe a consensus could bring more coins, but the block reward should change and the having times should do it too. Is a complex task.
I think it would be easier to add more zeros after the point than adding more coins to the blockchain, and both would have the same effect.