This is how I build a group on Roll20:
I run a number of one-shots on the day and time that I would like to run a regular game. I invite the best players of those groups to future one-shots. My criteria is that they play well, get along with each other, sometimes DM for others, have decent tech/skills, and are, most importantly, funny. Then once I've built up around 8 to 10 people, I offer to run a regular game for 5 PCs at a particular interval and leave sign-ups open to all, first come, first served. As long as we get 4 PCs from the player pool to commit, we play (which means we almost never have a cancelled session). Then I just run the occasional one-shot after that and, if I see someone really stellar, I invite them to the player pool.
Running and playing D&D online is not quite the same as running in person, but it has many advantages. You have a larger population of gamers from which to build your ideal group. In the particular setup I describe above, as long as the DM can run a game, there's almost always a game (which is sweet for me as I usually DM). Scheduling headaches and cancellations are almost nonexistent since you have more players than seats. And I also feel that without the distractions that can come with a table and faster play through dice rollers and the like, we get a lot more done in a given session without sacrificing on the fun. (For in-person games, I still use Roll20.)
Anyway, it's worth a shot and you can likely include your remaining players into that player pool - unless you just want to clean house.