Before you over-gear Rebel and Empire, wait to see about Geonosis TB. It may make your work for Hoth obsolete.
G8 zPalp Empire team and G8/9 Phoenix will do well to Hoth TB Phase 5.
I suspect that there is no reason now to gear towards Phase 6 missions since by then you should perhaps be doing Geo TB for better rewards.
Rogue 1 is likewise somewhat less useful now until you can spare resources since Galactic Republic toons/ships may be required for Light Side version of Geo TB.
Brood Alpha and Wat are the new HothCaptHan/ROLO&IPD.
So, perhaps gear for HSTR and arenas for now, ignore IPD/ROLO missions and get ready for Geo after we get feed back on requirements.
Can't go wrong with Bossk, Boba, IG88, CadBane with ships (add Dengar for Chewie and Greedo for HSTR P3 "Bounty & the Beast" and Embo HSTR P1). B&B also needs JKAni, Chewie, DeathTrooper.
Add Revan Jedi (Basti, GMY, Jolee, HermitYoda), [add Ezra until you get revan and don't zeta Basi Lead]
Hopefully those @ G12+ (Bounty hunters and Jedi) will be of some use in Geo TB as they are for Raids and TW.
Note: With Geo consolidating power in Guilds, you may find guilds Geo TB ready before being HSTR ready since HSTR ready players may leave to jump to Geo TB ready guilds.
This consolidating into more powerful guilds also makes JTRey more obsolete. If you have Embo Bountyhunters P1, a quick P3 B&B, and then Revan for any of P1-4 if you can squeeze them in as the raid goes really fast. Add Night Sisters P3 or 4 if there is time and hope they may have a Geo Night Sisters mission as AssajV is also a Separatist!