If Pokémon Red/Green/Blue were never officially localized outside of Japan, the Pokémon franchise as we know it today would likely not exist in its current form. The popularity of the series outside of Japan is a crucial factor in its success, and without that success, it is unlikely that future games would have been released outside of Japan.
Without the Pokémon franchise's success, it is also possible that the Game Boy might have been discontinued earlier. The popularity of the Pokémon games helped drive sales of the Game Boy, and without that boost, it is possible that the handheld console would have struggled to compete with other portable gaming devices.
In terms of pop culture, the absence of Pokémon outside of Japan would have a significant impact on the world of gaming and entertainment. The franchise's influence on video games, anime, and merchandising is immense, and without its success, other franchises might have filled the void, changing the landscape of pop culture.
It is also possible that fan translations of the games would have emerged, as has happened with other Japan-only games. However, without the official support of Nintendo, these translations would likely be more limited in their reach and impact.
Overall, the absence of Pokémon outside of Japan would have had a profound impact on the world of gaming and pop culture, changing the course of both industries in significant ways.