As subject goes, is Bitcoin the maximum version?
Is it still possible to develop it?
or
Can we still expect better coin than Bitcoin?
Nothing in this world is perfect.Bitcoin is far from perfect.It's development will continue forever.
If we compare Bitcoin to all existing altcoins,yes it is the "maximum version" of a cryptocurrency.
Yet,still Bitcoin Core has it's own issues,that have to be solved,in order for BTC to gain mass adoption and become a real global currency used by billions of people.