Nintendo buyers are too cozy towards Nintendo (and reap respective negative results). The "Pro" would arrive 4.5 years after the launch of the Switch, which is more typical for a complete cycle of Nintendo hardware, same goes for the alleged high price. For comparison, Sony released their PS4Pro just after 3 years, excellent timing. Would you spend $399 for an incremental update so you can spend that money again in maybe less than 2 years for a true successor and would you feel tricked afterwards? I hope it's not another XBOX One X (too late, too expensive, aborted after 3 years, not forward compatible).
I mean, you're the only one that's suggesting that Nintendo will be releasing a true successor in 2 years. Nintendo themselves have made no comments hinting at such a strategy, if anything, they've actively been confirming that they plan on supporting the Switch for an extended lifecycle, something that would make sense given the strategic decisions that they have been making thus far. Also, define "Incremental". Given what we know about the Switch's capabilities I see no reason to believe that it is any less of a revision than the PS4 Pro, which mind you, wasn't exactly a massive, generational leap forwards, it was basically just a duplication of the PS4's performance at a higher resolution. Also, why is it that you say that Nintendo will release a true successor in "maybe less than 2 years?" Why is it that you believe that Sony's strategy lacks any sort of major weakness, yet continue to hold fast to the belief that Nintendo doesn't know what they're doing with the Switch and will simply repeat the poor decisions of the past? If anything, the continued success of the Switch should already prove that Nintendo is not exactly keen on repeating its past mistakes.
But to get back to your other point, namely your belief that the Switch's lifecycle will soon reach a premature end, why is it that Nintendo is releasing a "Pro" model 2 years after Sony did for the PS4? This is a data-focused website after all, therefore maybe we should take a look at the numbers. In the year since the period that you stated would be "excellent timing" for a new revision, the Switch has sold nearly 50% more than the PS4 did during the equivalent timeframe (28M vs 19M). Keep in mind the PS4 had already received an upgraded model, a cosmetic refresh, and a price cut by this point, while the Switch has only received a minor budget SKU that constitutes less than a quarter of its overall sales.
The reason why Nintendo hasn't released a Pro model as soon as Sony has is simple; Nintendo simply has enough demand for the current lineup, at the current price point, that there simply isn't any economic motive to release a refresh sooner. That's the same reason why it took 9 years before the GBC launched. For Nintendo, the launch of the Pro this FY would be great timing, as it would allow them to sustain interest in the Switch following a year in which demand for it has increased exponentially. Clearly, Nintendo intends on keeping sales of the switch at its current record-breaking peak, and naturally, given the decisions that they have made so far, it would make sense given how much demand there still is for the Switch, that Nintendo would therefore postpone the development of its successor, a sentiment that they have already shared with the public. They recently said that they have no intention of releasing a successor anytime soon, and while this might be hard to take a face value, given the points I have just mentioned, it would make perfect sense that Nintendo intends on following through with its word, and as such, I find that there is clear evidence to support the idea that any successor to the Switch will most likely not be coming anytime soon, probably at the earliest 2024
Given the fact that I am still new to this forum, I am not yet able to make dedicated threads yet, but I can say that I am currently working on a new thread addressing this very issue, namely the belief that Nintendo intends on cutting the life of the Switch short by releasing a successor soon. I'm not sure how far I'll get, but hopefully I can share more of my thoughts on this subject sooner rather than later.