Apple is doing quite well under Cook. Same with Google under Pichai. Microsoft had some pains during the Balmer years, but I think that's partially due to the anti-trust suit making them gunshy and Balmer being a generally poor choice as a tech CEO, but they are doing very well with Nadella.
I expect Amazon to be as ambitious as ever. Though, I am slightly afraid of a shift in focus towards AWS over retail. But I suspect Jassy's selection had to do with fears that a pick from the retail side may see Jassy as a threat and may seek to undermine AWS in an effort to keep him in check.
Google isn’t doing all that well under Pichai, they haven’t launched a successful product under him since Chromebooks (I guess GCP, but when you are that size and <10% of market share, I don’t know if it’s successful), and they are just coasting on ads, YouTube and GSuite. Whereas Apple (say what you will about Cook) has launched AirPods, the Apple Watch and Apple Silicon-based Macs, which are all raking in cash. It’s possible that Google is only ever going to be an ads company, but based on their corporate rhetoric I don’t think that was the goal.
Apple Silicon Macs aren’t really raking in cash yet, but Mac sales are up $1B in the last quarter, so by time transition is complete they will be.
Google is doing poorly, but they have a monopoly on web advertising. If they lose that they'd be in trouble. They also weren't doing better when lead by Page (Google+ era).
Microsoft was on the path to irrelevance during the Ballmer years and Nadella has pulled off a miracle to save them.
I hope Amazon is more of a Tim Cook story than a Steve Ballmer one.
> I suspect Jassy's selection had to do with fears that a pick from the retail side may see Jassy as a threat
Amazon had (has) three CEOs: Bezos as overall CEO, Jassy as CEO of AWS, and Jeff Wilke as CEO of the "Consumer" business, i.e. the retail operation.
Wilke announced last year that he would be leaving and that SVP of Operations Dave Clark would replace him as head of the Consumer business.
The question is whether Bezos chose Jassy and that made Wilke leave, or whether Wilke leaving left Jassy as the only remaining choice to replace Bezos.
I expect Amazon to be as ambitious as ever. Though, I am slightly afraid of a shift in focus towards AWS over retail. But I suspect Jassy's selection had to do with fears that a pick from the retail side may see Jassy as a threat and may seek to undermine AWS in an effort to keep him in check.