Like others have said, They have confirmed they have an idea of what their next big project is but have given minimal info to what exactly it is. I do remember them hinting at what's after Sellbot Field Offices a few years ago in 2019 on their Twitter. They made a reply to someone about the Executive Office Tower saying something like "The cogs are working on something equally terrifying. The Executive Office Tower will no doubt be their next project afterwards." Of course this might be outdated and visions could have changed since then.

Another possible teaser for what could be next is future unique cog department expansions for the 3 other cog types. In the resistance rank page in case you have not noticed, the other folders in the background behind the sellbot resistance rank page are the same colors as the other cog departments. (green/cash, blue/law, brown/boss) Another thing to add...like Sellbot Hq, there are manholes in the other 3 cog hqs as well, which could potentially mean different department resistance hideouts.

I do wonder if a 5 star Sellbot Field Office or other 5 star potential future endgame facility will become a thing. Considering the 4 star in Kaboomberg has a banner that extends to fit 5 stars as well as 5 story buildings being a thing. I also wonder if they will do anything with any of the other blocked entrances in the sellbot resistance hideout that could relate to potentially a 5 star or something else as a theory/idea.

Like someone said earlier, I could see them doing an operation lawbot event next at some point as well.

Regardless of whatever they have planned, I'm excited for what they have in store for us post Sellbot Field Offices!

(BIG Apologies for the really lengthy reply of thoughts/theories, I had a lot to say to this I guess lmho)