This was just announced today in Konami's official YouTube channel (I don't know if this was shown at E3 or not?) that they are showing an official TurboGrafx-16 (PC Engine Mini) will be coming. This was very unexpected from Konami themselves to reveal to see the TurboGrafx-16 is finally getting to the Mini Retro Video Game territory like the NES & SNES Classic Edition and the Sega Genesis Mini.
List of games showed off from the trailers as of right now and more TurboGrafx-16 games will be announced soon:
R-Type
New Adventure Island
Ninja Spirit
Ys Book I & II
Dungeon Explorer
Alien Crush
Super Star Soldier
Castlevania: Rondo of Blood (Showing in Japanese trailer only as of right now)
Some Japanese title that I don't know about (The one with Kung-Fu had "The" on the title and showing in Japanese trailer only as of right now)
Bonk game (I don't know which one it was and showing in Japanese trailer only as of right now)
It was nice to see Castlevania: Rondo of Blood was shown in the Japanese version, I don't know if it's going to be included in the Western versions list? I do want to see Castlevania: Rondo of Blood on the TurboGrafx-16 Mini with the English audio from The Dracula X Chronicles and Requiem port.
TurboGrafx-16 Mini Trailer (North American version)
PC Engine Mini (Japanese version) Trailer
PC Engine CoreGrafx Trailer (I think this could be the European Trailer)
Update from July 11, 2019: Konami revealed the release date is 3/19/2020 and will be including All of 50 games in One.
Update from July 15, 2019: Pre-Order is now live and US Price is available.
Update from August 7th: Konami revealed 7 more games which are Namco games in the TurboGrafx-16 Mini will be the final list.