If Nintendo wanted it probably could be compatible, but they want people to buy the new Switch.
For me, if games on Handheld Mode are in 1080/60 then I'm satisfied and won't use the Dock Mode. I did buy a third party Joy-Con NS2 Chargeable Grip Controller so I'll have a controller I can use for TV gaming.
NS2 Pro Controller looks mostly the same as NS1PC, with a new C button (wake mode) and back buttons (never cared for that).
NS2PC doesn't have analog triggers so, meh, pass.
Might try to buy a GCN NS2 if I can find.