First off, I never really cared for the bloke. He had cool threads and a cool ship.
But a lot of folks love the dud.. err.. dude.
He is iconic, so he has to show up. But how to do it?
My thoughts are this; make him (and other fringe/scum) units as a universal upgrade - now hear me out.. this univerasal faction (which we will call scum) can be done a few ways. Certain imperials used scum. So, being able to take Boba works thematically. He should certainly be a special forces - heck, most named scum should.
That being said, Boba should not be named as Part of the imperial faction. Luckily there is a way around this (and incorporating other future factions), what the faction is aligned with. Light Side or Dark Side. The empire is certainly Dark Side, and Boba should be too. That way as a special forces slot, you can take him.
Now for the second way to play scum: you should certainly be able to play them. But a scum army should be different. They very much should not have the same army stipulations. Perhaps lacking a “commander”. But maybe a few more special forces slots. Then you could designate a commander with the token. Fielding a scum faction should make you choose between light or dark side units.
Now, here is the idea for the THIRD way to play the game - the trickiest part; and I've suggested this for random beasts, that of a battlefield condition. You could have the likes of Boba Fett hunting down a unit, or your armies commanders.
Doing a scum release as having three ways to use them will also help their sales as some rebel players may want to use Boba as an obstacle, some will want a full faction, and others just want to field one or two scum units in their army. Scum units, names ones at least, should be powerful and expensive.