If Apple are developing new OLED/microLED/miniLED screens then it may make more sense to include touch sensitivity as a standard part of the manufacturing process than add the logistical expense of making multiple models (esp. as they'll want to use them for iPads as well). You mention 3D TV - there was a period when it was virtually impossible to buy a mid/high-end TV set that didn't have 3D support - a mixture of economy of scale and not wanting to be left behind - and that would doubtless have continued had the world not come to its senses and realised that 3D TV was an vastly dumber idea than touchscreen Macs (3D movies being a stupid, impractical idea that has bubbled up every 20 years or so since the 1940s). It's still the case with "smart TVs" - I'd love to be able to buy a "dumb TV" and rely on easily-replaceable external boxes, but the reality is that economies of scale would probably mean that would cost the same - and probably more - as a smart TV.
Reality is that a lot of the PC competition to the MacBook range includes touch screens as standard (or standard when you upgrade to a "retina"-equivalent display). We're not talking bargain-bucket cheap PC laptops, but the ones pitched at the MacBook end of the market, like the MS Surface Laptop or the higher-end Dell XPs. ...and while the Mac Faithful might not care about this, Apple do have to care about attracting fresh blood from the PC-buying public, and missing a "tick list" feature is not good.
Then you have the mobile market, which is all touchscreen, and a world were websites and apps are increasingly being designed for mobile first, PC second. Not having touchscreen could become a liability on a very short time scale.
Apple already support running "native" iOS apps on MacOS - most developers have been reluctant to opt in for a variety of reasons, technical and business, but one good reason is that an App designed for touch might not work well on a non-touch screen. Apple are also providing new App frameworks that make it easier to build MacOS and iOS Apps from the same code - so offering Apps with both touch and pointer interfaces should be easier in the future.
The other application for touch may be with audio/music apps - virtual instruments and on-screen mixers are crying out to be operated via multi-touch rather than a pointer.
I take the point about Windows 8 - but the flip side to that was that besides 'forcing' touch interfaces onto laptop users it was part of a futile Microsoft effort to force Windows onto mobile users - a market they'd already lost to Android and iOS. It came with an "App Store" full of crickets and tumbleweed. Anyway, Windows 10 was only a partial rollback - it still had touch-friendly elements - and was generally successful (although MS have a huge, unrelated problem of corporates running 'legacy' software who really just need Windows XP to be supported forever...)
Apple have the biggest/best catalogue of quality touch-screen software for iPhone and about the only substantial catalogue of serious software for tablet devices - much of which just needs the developers consent to run on MacOS. They're in a much better position than MS to produce a hybrid device.