The 90D and M62 are fine still cameras with good amateur video capabilities. I'm sure they will sell well. Or as well as they can in this shrinking market. But the lack of 24p and the upscaled video* are going to send a number of buyers to other cameras. Some of those people will go ahead and buy a 5D4 or an R. Others will simply buy from another brand. Canon marketing apparently thinks the risk is worth it, that up sells to Canon equipment will out weigh losses to the competition. But I have my doubts.
The commenters here who are defending Canon's decision keep saying...directly or through sarcasm...that the target market does not need 24p. But that's an overly simplistic view of potential buyers. As but one example: if the 90D had oversampled 4k and 24p it would be my cinema/backup camera, compatible with all of my EF glass and offering extended reach and frame rate in wildlife and sports scenarios. I'm not the expected 'target market' yet I could still be a potential sale. But with hobbled video it becomes a no sale. I've been waiting a while for Canon to offer a hybrid to fill that empty spot in my bag. It looks like that spot will go to an X-T3.
There are many other examples. The vlogger who wants excellent 4k 24p. The film student on a budget who wants the same. The serious amateur or pro who wants to mix cameras to the same timeline. The guy buying a B camera to his "real" cinema camera. That's real money Canon is throwing away.
Now I'm not "abandoning Canon" nor do I think they are DOOMED. I've said repeatedly that I think 5Ds IQ is phenomenal, and I have nothing but glowing words to say about my L lenses. Add to that great AF, great IS, gorgeous color science, and best in field ergonomics. (And weather sealing. Let's not forget weather sealing cough Sony.) My stills kit overhaul was intended to satisfy me for years, and I could happily shoot that equipment for the next decade.
But some people will look at their budgets and their existing gear and decide "...if brand X can do everything I want and Canon won't even give me simple features, why not jump?" Those can be quite expensive losses to Canon. We keep talking about their marketshare but their profitability suggests they're shoring up marketshare through entry level sales. They also need prosumer and pro users who keep buying upper tier bodies and lenses over the long haul. That includes social media influencers: vloggers that some deride as 'the next Spielberg' or just some 'YouTube talking head.' Make fun of them all you want, but they drive sales. The last thing you want is some YouTuber making fun of your 90D with an animated 'cripple hammer' swinging around the screen. No, you want guys like JP and Tony to be screaming "OMG I can't believe Canon did it YOU WANT THIS CAMERA!"
As for up selling to the R: that strategy might have worked on me if the R was FF oversampled 4k. Or at least a relatively mild 6k crop out of the sensor to 4k. But with its severe crop it feels like yet another compromise, like Canon is trying to up sell me again. Trouble is, for stills/cinema hybrid they don't have anything left to up sell me to. But the competition does. I would have really, really loved to maintain a Canon only kit for the lens compatibility and ergonomics. But Canon seems bent on preventing me from doing that.
* The rumor here is likely correct. For full width readout Canon is either oversampling, binning, or line skipping. If they were oversampling then full width 4k would be better than crop. Hell, they might not even include the crop mode. Someone probably grabbed a frame from a sample video and figured out the actual recording resolution. This is worrying because it suggests that even with a new sensor, Canon still can't do oversampled 4k. Hybrid stills/video is only going to become more important as time moves on. They need to solve this.