Fees are calculated per byte not per transaction so a miner is notionally indifferent to mining 5 normal or 10 Segwit transactions. In reality I suspect that miners are anti-Segwit because less congestion would be less fees.
And for now, it's OK for Bitcoin network rules : https://bitcoincore.org/en/2016/10/27/segwit-upgrade-guide/
Quote
The segwit soft fork has also been designed to be both backwards and forwards compatible with all commonly-used wallets, so wallet developers and users can also independently decide whether they want to adopt segwit or continue making transactions without segregated witnesses.
We can fix that.
Users (full nodes) must enforce segwit transactions.