Is a Super Mario Galaxy Switch port possible?
Super Mario Galaxy came out in 2007 and was one of the top selling games on the Wii, at 12.79 million copies sold, the 9th best selling game on the console. The sequel, Super Mario Galaxy 2 was released in 2010, sold 7.41 million copies, coming in at #13. It's been over a decade since we first got to experience Mario's space adventure and the introduction to special gravity effects.
As of now, there has been little news or rumors about porting the pair of iconic 3D Mario titles to the Nintendo Switch. But given how much Nintendo loves to port games to the Switch, it's something you definitely can't rule out.
Super Mario Galaxy in HD in Switch portable mode...
At first glance, the Switch doesn't have traditional motion and pointer controls like the Wii or Wii U did as there is no sensor bar with the system. Motion controls were a significant part of Super Mario Galaxy and Super Mario Galaxy 2.
However, the Joy-cons and the Switch Pro Controller both feature gyro/motion controls that have pointing capability. This has even been demonstrated in Captain's Toad: Treasure Tracker where you can have an on-screen pointer to "touch" objects on the screen. The functionality can be borrowed to allow the collecting and shooting of star bits, which is one of the main functions used during gameplay. Similarly, Yoshi's tongue action ability from Super Mario Galaxy 2 can also be controlled in this fashion.
Once this main blocker for the controls is overcome, a port of Super Mario Galaxy shouldn't be overly complicated. It can continue to play like any other 3D Mario platformer.
For Mario's spin move with Luma, standard motion controls by shaking the controller can be used. There is a low level of precision for this movement, so it can be easily implemented. Alternatively, they can also simply map the spin move to a button on the controller.
When playing in the portable handheld mode, the touch screen can be utilized to grab star bits, and along with shooting them - perhaps while holding one of the ZL or ZR buttons.
In terms of graphics, the weak Wii hardware severely limits the quality of graphics of the Super Mario Galaxy games. The Wii was released in 2006, and the first Galaxy game was released in 2007, just when HDTVs started to become commonplace for households.
Graphics wise, it might not even require much work to upgrade the graphics to HD quality - when run on emulators, the two Super Mario Galaxy games were shown to have outstanding upscaled HD graphics on par to what we've seen with Super Mario Odyssey on the Switch. In fact, Super Mario Galaxy already been officially released in HD on the Nvidia Shield in China.
Super Mario Galaxy in HD on the Nvidia Shield, no reason the Nintendo Switch can't do this...
Super Mario Galaxy looks amazing with HD graphics, it's quite unfortunate that it was completely bottlenecked by the underpowered Wii hardware, and the Wii U did not offer an HD upscaling functionality. Nintendo can right a wrong by giving these amazing games the graphical upgrade they deserve.
TL;DR - Yes, a Nintendo Switch port of Super Mario Galaxy should be able to be done without making wholesale changes. Ideally, Nintendo should release both of them as a 2-in-1 bundle and that can be another rehashed game they can continue to milk your money for!