I think it'll be hard for GF to make anyone happy. Pokemon does not operate like Zelda, Mario, or any other conventional video game franchise. It's a multimedia empire. So its both a blessing and a curse, however you want to put it.
With how TPC, Nintendo, and GF operate, in terms o the games, the anime, the TCG, the merchandise, etc.; having to keep up with all of that can be hard to develop grand games, even under a 2-3 year development cycle and having to release them under an annual/bi-annual basis.
That's their own decision. They don't have to release on an annual/bi-annual basis. They can simply stretch out and extend the generations to give themselves that extra time they need to make grand games. And hire more staff and resources as well. As I've mentioned many times before, Pokemon is the biggest multimedia franchise in the world. It's exactly like you say, an empire. They can have all the resources, staff, and tools they want. They simply choose not to.
The only years where there isn't a Pokemon game (new gen, remake, third version, or sequel) are:
1997, 2001, 2005, 2007, 2011, and 2015
They would have to rework how they model their releases from all their multimedia projects.
How long can the anime be? It usually lasts for about 3 years until the next generation to align with the upcoming new generation of games.
Just make more episodes and pad out the generation. Nobody cares how long each series of the anime goes. Furthermore, doing so could add to the legs of the mainline games that said anime is based off.
How will TPC continue with the merchandise and TCG series without a mainline Pokemon game for maybe 3-5 years, instead of 1-2 years?
The merchandise is by far the most profitable aspect of the franchise, it will keep selling no matter what. That train cannot be stopped. And they can do the same with the TCG that they would do with the anime.
Pokemon has garnered billions from all aspects of their media projects using the model that they are using as of now.
That means the likeliness of remakes (i.e., Gen IV), third versions, sequels, are gonna be lower than usual.
But again, are there fans who are ok with no new Pokemon for longer than 2 years?
I don't know if there is a simple answer to all of this.