Japanese publication Nikkei Style released an interview with Keiji Ota--Toho's Chief Godzilla Officer over Goji-kon, or the Godzilla Strategy Council launched in October 2014. The council was created to help decide where to take the future of the Godzilla franchise.
"...after 2021, we're thinking of a potential strategy that [releases] Godzilla movies uninterrupted at a rate of every 2 years, although there is a preference for a yearly pace as well." said Ota. He continued, hoping to expand Toho's Godzilla franchise into a cinematic universe, inspired by Marvel."
"The future of the series and its forwarding developments are very conscious of the method of "shared universe". Godzilla, Mothra, King Ghidorah, etc. could all share a single world view much like a Marvel movie where Iron Man and the Hulk can crossover with each other."
"It is said that each movie can be a possible film production where any one of them could lead a film of their own as the titular character."
Toho Godzilla universe will not include 2016's smash hit and Japanese Academy Award winning, Shin Godzilla.
"Shin Godzilla was a huge hit, but instead of thinking of doing the obvious idea of making a Shin Godzilla 2, instead think about a world that can be used for a long time, I'd rather make a World of Godzilla."
Toho seems completely dedicated to expanding the Godzilla franchise after 2020, with the tentative plan of a new film every two years and a fresh "World of Godzilla"