A new Wonder Boy game was just announced, called Wonder Boy: Asha in Monster World. It’s release is planned for early 2021, on both the PS4 and Switch: https://wonderboy.inin.games/
The game is essentially the next in series after 1994’s Wonder Boy IV and it appears the original team is coming back to make it: The creator, composer, character designer and creative manager have all reunited for this sequel. While there’s been some pushback from some hardcore SMS fans about the game’s look, I view it as a natural progression and what the games may have looked like if the team had the same resources available back in 94.
IGN has a bit more info for anyone interested and we’re certainly be keeping people up to date on it’s progress: https://www.ign.com/articles/wonder-boy-asha-in-monster-world-announced-led-by-series-creator
— ININ Games (@ININ_Games) August 24, 2020