I've seen several admins and bureaucrats demoted because of their inactivity. Long-time members who have had an enormous impact on the wiki, who lost their User Rights simply because they were demoted. Quite honestly, I don't think that's the best way to deal with things. Especially since one thread on SFW has brought up an alternative I think we should much rather use.
The concept is that rather than demote admins/crats, we mark their userpages with "Semi-Active" or "Inactive" templates. The point is, these are admins that have and still can do good for the wiki, but simply don't have the time to be active on the wiki. When you really think about it, we're ultimately telling these people "You don't edit enough, so regardless of how much good you've done, you're being demoted". And I don't think that's a good message to send OR a good way to treat people who contributed and cared enough about the site to be given such responsibilities. Sometimes, people just can't help that other responsibilities have overtaken their time for Sonic News Network. No matter how great or prevalent a site it is, it's still just a website; essentially punishing people because they can't find time to contribute really isn't fair.
That's why I suggest this alternative that was also suggested on SFW; by giving these admins templates marking them as "Semi-Active" or "Inactive", we recognize that they're still good, capable, and competent people who deserve the privileges they were granted. However, we also recognize that they're currently not involved with the site and shouldn't be looked to for advice or assistance until they can make a proper return to activity. In the mean-time, we can still promote new admins and bureaucrats to take over the duties that have been left behind. I'm sure this brings up concerns about their being "too many admins/bureaucrats" should the inactive ones return, but their continued competency can be brought up at the point of their return. In the mean-time, what these people have done for the site should be remembered and respected, not rendered null simply because they can't contribute often enough.
For an example of the SFW suggestion thread, please go here: [1]