The only benefit I've really made sense of with hybrids is their engine emissions aren't localised to the neighborhood where they're charged overnight. Apart from that, I can't think of anything else.
Conventional jet engines run at RPMs in excess of 20000rpm. To get this same speeds for the same mass flown rates of say a J79 (F4-Phantom) you'd be looking at some massive electric motors. Conventional jet engines would be using electric motors if they were light enough already.
There is a reason Rolls-Royce UltraFan uses a speed reducing gearbox for it's fan blades and not an electric motor.
More to the point above, at hypersonic speeds, using a conventional compressor is sort or useless unless you can keep your air cool.
I highly recommend AccuBattery for Android. I have been using it for a few years now and I saw a noticeable difference on my Pixel 3a XL compared to use on previous smart phones. I now have a Pixel 6 and its nearly 2-years old and the battery lasts well beyond 30-hrs with combined use.
How is China a problem? The way of life and the energy intensity of a single individual living in the developed world is the problem. Do I have to point out the US and Europe? (I live in the UK).
This is essentially the Boots Theory, coined my Terry Pratchett. The reason that the rich were so rich, Vimes reasoned, was because they managed to spend less money. Take boots, for example. ... A man who could afford fifty dollars had a pair of boots that'd still be keeping his feet dry in ten years' time, while a poor man who could only afford cheap boots would have spent a hundred dollars on boots in the same time and would still have wet feet. Men at Arms. p. 32.
There are a number of reasons why it might have failed, fatigue, deviation from process/protocol but pressure vessels are well understood and not the problem here.
Worth noting the use of titanium at Mach 3, Mach 3.5, is really at its limit. Any faster and you'll start to see serious problems with thermal management. This pushes you into using super nickel alloys or even ceramic matrix composites, which would be necessary for use cases at Mach 5+ for sustained flight. Acknowledging planes in the last have gone faster like the X-15 but this such plane's architecture wouldn't stop for longhaul flight distances. CMCs and super nickel alloys will be very very expensive.
And I think this is one of the reasons we are seeing so many companies racing to create a commercially viable eVTOL (electric - vertical take-off & landing) product. To me, this transport system only seems to be a solution to the problem mentioned above. I can't see them ever being commercially viable (FAA regulation, power density, etc.) And yet there are a lot of companies trying to make them a reality when really the cities they have renders of with their flashy electric vehicle flying over just need better public transport systems.