I don't think it's dying at all. On the contrary, Sedo is growing and growing. I have many successful sales there, and it is also my preferable platform to purchase a name.
Their parking stats can be good indicators on how to move forward with your names ie drop, renew, auction off, or even move to another platform that may generate better revenue.
Their support has improved considerably over the years, to the point where a simple phone call rectifies any sort of issue.
Now, as far as the website itself is concerned, I agree it's very outdated. They need to do some serious revamping of the whole system. However, it's not in bad enough shape to turn me off of them. Yet.