It will be some years before Starship can do missions other than Starlink with that payload dispenser system. There are also other issues under the hood they have to address. But yes when fully matured it will significantly disrupt the LEO (which is the future of space) market. Will take some years for market to adapt to this paradigm.
ULA is working to get their Centaur V upper stage upgrades funded. Would make for a very powerful space tug that would unlock new capabilities for deep space. The math on distributed lift for high C3 missions is nuts. Don't rule them out just yet. Even without all that, according to Tory Bruno they already sold 70 flights.