I would suggest, if thecoli2 is the next place, continue to upgrade the place and prep it for now. Going to take time and probably another outage before you get huge migration to the site unless everyone can get on board posting there for now.
But, if you end up making that site better than this place eventually with enough work (Fix embedded, no filters on cussing, enable custom smileys, feature page, etc), that will eventually drag more people to that site.
Once you get enough on that site that its starting to rival this site, more and more people will join because that is where the juice will be. Like it can be a backup for when this site goes down for now but if you dudes are serious, start looking to upgrade it to at least match features we have here until its a more attractive alternative beyond backup status.
If ya'll are legit wanting to do this thing, i'll help out as much as possible. Like first I'd recommend setting up a Kanban board or story board if you have multiple people contributing to build the site. Create stories/tasks to enable different features (i.e. set-up custom smileys, enable embeds, etc). That way you can have a structured way of incrementally improving the site over time. Like I said, if you guys end up really doing the shyt well, people will flock naturally as it will just be better, not to mention having engaged admins which this site is missing.
Another option as the above, just create a pull request system on github.com or something. People can submit feature requests, and you can track enabling the features there. If help is needed with that let me know.