luvflyin
Touchdown! Greaser!
You're referring to clearing other aircraft out of the way of the NORDO aircraft correct? Well, there's no standard procedure for that.
You can try and anticipate a pilot's actions because of 91.185 but that leaves a few what ifs. Like you said, the pilot could come back and try another approach, they might head off to a VMC field, they might land at their alternate or if their alternate doesn't look good, go to a different alternate.
Like Steven, never seen an aircraft that couldn't get in to their destination and then went 7600. If it did happen, yes, I would've had flight data call AFSS and get the pilot's alternate because there's a good chance they'll be heading that way. That would take all of a minute to get. After that, you monitor the track of the aircraft. Basic radar sep from them would be 1000 vert or 3 miles horz. Vector or assign altitudes to other aircraft to deconflict. If the aircraft appears to be leaving your airspace, handoff the aircraft to the next facility and let them monitor the aircraft's progress.
From the OP. "Say the weather is less than the 1-2-3 required to file an alternate. Yet, I neglect to file one. What happens?
Yup. Thats about it. There will be 3-4 people standing around watching, coordinating and paying real close attention to you. Then you land and you don't get in trouble with FSDO because you didn't file an alternate.