1. Take-Two: get your stuff straight and tell Rockstar to port GTA V on the Switch

SquEnix Japanese side. - Concentrate on developing FF and JRPG (new Valykrie Profile, something from Ivalice team etc), get FF games to a every 2-3 year release. While other companies like EA, Ubisoft and Activision are taking their biggest game series and turning them into yearly regulars, service games or game with constant DLC, They don't have to do this level of stuff but more than 1 a gen would be nice. SquEnix have released 1 main series title FF game this gen, 1 last gen too (I don't count sequels and MMOs).

Capcom - Get back to making fighting games again... I just want a new Star Gladiator, Rival Schools and Darkstalkers.

Square-Enix:

1) Hire back the original Final Fantasy team and have them make Final Fantasy from now on (Sakaguchi, Uematsu, etc...).

2) Use all of those Western studios you've purchased to do the graphics on your Japanese games like Final Fantasy, Kingdom Hearts, etc....  These are the games that people want most and they come out too slowly.  Also Western studios do a great job on graphics, while gameplay, music, story, etc... should still be handled by Japanese teams.

3) Bring back Final Fantasy Tactics series and put it on Switch.  Really I should have made this #1, it is easily the most important thing.

4) Expand your Octopath Traveler style team(s) and have them remake Final Fantasy 1 - 6 in the style of Octopath Traveler.  After that have them make more games of this style.  You really need to up your game output and this is a great way to do it.

Oh yes, please, please, please.

Nintendo - go third party so I don't have to bother buying your device, like you did with Mario Kart 11.

Square Enix: I'd get them to abandon their (seemingly) company-wide visual kei art style, stop announcing projects the second they're green-lit, give Naoki Yoshida the reigns to FFXVI, get better scenario writers for Final Fantasy and get a better western marketing team.

Game Freak: Use their profits to expand the company to, at least, 2x their current size, hire better programmers and have enough common sense to ask Nintendo for help when they obviously need it.

Well then, hope you didn't want Metroid Prime 5. 

EA: Sell NFL rights to Take-Two or Sega, sell FIFA rights to Konami, sell off what's left of Bioware, disband, and I retire to Sedona AZ.

Activision/Blizzard: Meh. They're just there as far as I'm concerned. 

Square Enix: Final Fantasy XVI. Completely off line. Yasumi Matsuno, Hiroyuki Ito, Akihiko Yoshida, and Hitoshi Sakimoto as the leads. Valkyrie Profile 3. Dragon Quest XII. Complete collections of Final Fantasy and Dragon Quest. 

Sega: Valkyria Chronicles 5, maybe with a Korean War theme or a Guld War theme, and Sakura Wars, and back them with a huge development and marketing budget. Get a deal with Nintendo or Sony to make VC5 a headline game for the Christmas season. Virtua Fighter 6. Figure out who owns the rights to Lunar and obtain the rights, hire Toshiyuki Kubooka, Noriyuki Iwadare, and Kei Shigema. Have them do a full 3-D anime RPG that looks like VC or Ni no Kuni,

Konami: Castlevania, Contra, Suikoden. Also obtain the rights to the Simpsons, Futurama, and Disenchantment. Outbid EA on FIFA and make PES the official FIFA game. Not a huge fan of soccer, but I'd like to see EA humbled.

Bethesda: Fallout 5 single-player with heavy-duty RPG elements a la the first two Fallouts and New Vegas. 

Capcom: A real Breath of Fire VI. A true sequel or spiritual sequel to Okami on console. 

Nintendo: Mother 3 in the US. Obtain the rights to the Ultima series, hire Lord British as a consultant at the very least, make a new Ultima game. Joint development between Monlithsoft and Obsidian.

Ugh, we Arizonans don't want 'em!

Dump 'em in Texas or something.

Konami: make games again, and stop slave-laboring your employees.

Valve: learn to count to 3 and make Portal 3, Half-Life 3 and Left 4 Dead 3.

Sega: make Virtua Fighter 6, Sonic Adventure 3, make House of the Dead: Scarlet Down for PSVR, make Phantasy Star Online 3, make Alien: Isolation 2 for PSVR.

About all I can think of ATM.