The beauty of Linux is that it's open. Ubuntu is just a distro. Few of the people who use it today, did so half a decade ago, and most can easily substitute a different distro if/when Ubuntu no longer satisfies.
I use Ubuntu, but the thing is, I don't really use *ubuntu*, I use Firefox. I use Eclipse. I use Thunderbird. I use php. I use gcc. I use a dozen other programs, but ubuntu itself isn't a significant part.
The distro needs only be easy to install, easy to maintain, and capable of launching the programs I actually use. Atleast half a dozen distros fulfill these requirements today.
Key lesson is that a software-vendor can only screw you over to the degree you've made yourself dependant upon software that is only available from them. Don't do that if and when you can help it.