Moving this on over to the 7th Gen forum!
And personally, I think it's still worth it, considering the only Pok?mon Switch title we know of so far will be Kanto remakes coming out in November - this is dependent on if you've played SM or not already IMO, but if you haven't and you really want to experience a newer region, then I'd say it's worth it.
I'm not sure if 3DS Pok?mon will be transferable to Let's Go, haven't stayed too on top of the Let's Go news so maybe someone else can help with that!