So you can release rm2k3 games on steam now also?
Yes, as long as you own the rights to all the resources or they have license to be used commercially.
Considering how wild west style RPG Making used to be, I wouldn't use any of the older resources as they have no clear TOS unless they were specifically done for you or by you.
Maybe one day they'll release RPG Maker 95.
They did release RPG Maker 2000 too.