Dragon's Dogma sold .04m copies on Xbox One, and Capcom still released Devil May Cry 5 on Xbox One. So, this confirms that Dragon's Dogma only has to sell .04m copies on Switch to be considered a success, correct?
Porting between the X1, PS4, and (Windows) PC is relatively easy because they all share the same architecture and have enough power between them to not have to gimp on any assets. That is not true with a potential Switch version. Nintendo decided to not even attempt parity with the PS4/X1 and thus any port job of a game that uses the extent of resources that the PS4/X1 has will require at least some tweaking to get it running on a Switch. If Nintendo released a console with similar specs as PS4/X1 and based on x86 architecture then Capcom easily could have ported DMC5/RE2 Remake/etc. They didn't, because they know their strength is their first party titles and portability, and they made the right choice.
As I say it again and again: as a developer I can assure you, that compilers take care of different architectures these days without any problem. What you probably need though is the engine it is running on. That Switch got with Unity and Unreal the two most important engines has certainly a positive effect on ports (compared with WiiU, which didn't got Unreal).
The second part though is more relevant. Yes, with lesser power you have to gimp assets or effects. Not super difficult though, but you have to put some resources into it.
The most important part is left out by you: cartridges. Cartridges hold a lot less memory than optical discs. Optimitzing assets for that is a pain in the ass. Again not impossible, but this actually needs effort and time (and therefore money).