If armor is removed entirely (and that is a big if), instead of trying to find a new role for every fleet ship type designed around armor or countering it, the ones who have "obvious" repurposings can get those, and the rest that can't find a good, non-silly type "repurposing" or "gimmick" to take their place just "go away". They wouldn't really go away truly; save games where you have one of the removed types unlocked will remain unlocked, and existing ships of those types will still be there too. However, they wouldn't be availble as options to players or humans for subsequent games or unlocks. Basically, it would be like that neinzil carrier type bonus unit that was scrapped during the beta.
I know that removing a bonus ship type that has had a history is a pretty big move, but TBH, the game is already on the edge of the point where the sheer variety of bonus ships is starting to hurt the quality of the game rather than be an asset, so I don't think the "metagame" will care very much if 1 or 2 less popular ship types go away.
The only ones I can think of that don't seem to lend themselves to an "obvious" re-purposing are the anti-armor ship, the zenith polarizer, and the human hardened forcefields.
Either the polarizer or the anti-armor ship I guess could be repurposed to have implosion artillery ammo*, whichever seems more thematically appropriate. The other one can be "phased out" as described above.
As I mentioned previously, the human hardened forcefield generators would be removed, and either the regular human forcefield cap doubled or the regular human forcefield HP doubled (I would lean towards the doubling of the cap), but not both obviously.
The autocannon minipod could just get a moderate DPS buff or a small DPS buff + small HP buff.
The armor-rotter, as suggested by others, could gain a new DoT mechanic.
The armor fleetship could just gain more HP.
The space tank could be repurposed to be a "slow-mover" like the armor fleetship is, but with focus on DPS instead of HP. (Or the armor fleetship could be sped up to match the space-tank's speed)
The armored golem and heavily armored AI superweapons would just get a simple HP buff.
The planetary armor booster could instead do something like reduce all direct damage taken by friendly ships in the system by 25% or something like that ("special effect" damage such as attritioners would be unaffected)
The planetary armor inhibitor could instead do something like increase all direct damage taken by enemy ships in the system by 20% or something like that ("special effect" damage such as attritioners would be unaffected). Not sure if it should keep the enemy forcefield disabling properties or not. It's a great side benefit, but a rather unintuitive one as it is a remnant of when they were called planetary shield inhibitors.
The neinzul youngling nanoswarm could just have the other "debuffs" buffed slightly, or it could be given a pretty darn small DoT (the DoT would need to be stackable in this case, and there probably should be a max-DoT rate as well proportional to the max-HP of the affected ship. Same would go for the armor rotter too)
The raid starship is a little trickier, but a moderate HP buff, but let it keep its radar dampening, hopefully would keep its dynamics mostly intact.''
Any other armor-centric ship types I missed?
*BTW, I still think that ships with an implosion artillery ammo type need a hard cap on min and max damage, regardless of percentages, though those bounds can vary based on ship-type to ship-type of those with implosion artillery ammo type)