Lol, so Switch will sell less than the 3DS even though it's been outpacing it since the beginning? This is also factoring in 3DS had a hard drop in year 3-4. What's going to make Switch have such an emphatic drop where its going to hault enough to sell less than the 3DS??
To give you an idea of what I did, I basically took the 3DS and compensated for price difference. I know that it is shocking for it to be near 50% of sales, but in all reality, I do expect a portable PS5 and more realistically, I don't see how a hybrid console of the Switch's stature can compete with a PS5. I think that Nintendo will want to recapture 3rd parties and I think that they are going to need something more powerful. I expect Nintendo to release a new console cabable of playing switch games but much more powerful. Like Wii to Wii U or DS to 3DS.
more unrealistically you mean. A portable Playstation would still not come close to PS4 power without sucking the battery dry in a millisecond or being heavy as a brick.
But also remember that the year Switch came on the market was also the best year of the PS4, simply because they barely compete. The release of a PS5 thus has close to 0 effect on Switch sales.
While I do think this year will be the peak of the Switch (due to most heavy hitters having been released by end of the year), I don't expect the sales come crashing down anytime soon. Rather, I expect them to be plateauing for a year and then come down slowly.
In fact, unless the PS5 would be released this year or next spring, it's quite possible that the Switch will be very close to those 65M already by the time of the PS5 release