ハムスター浜田「500タイトルの権利を持っています。Switch向けには出来る限り多くのタイトルを出していきたい。」
They also talked about third-party Arcade Archives titles on Switch. Hamada noted that at the Tokyo Big Sight event last January,
the Arcade Archives logo was included in the third-party list for Switch.
So he would like to include as many games to Switch as possible, as long as they don't have licensing issues.

It is possible to port the other Arcade Archives titles currently available in other consoles, and Hamada would also like to release games which licenses are held by arcade game maker companies of the past, like Nihon Bussan, UPL, and NMK.
Right now Hamster holds the rights to roughly 500 titles. Although some of these games are still difficult to release today,
Hamada wants to release as many as possible.

https://nintendoeverything.com/hamster-on-the-process-of-making-arcade-archives-mario-bros-for-switch-working-with-nintendo-much-more/2/

switchタイトル500本増えるらしいね(´・ω・｀)