I do even less than 20% of what you do in terms of cardio and I'm maintaining below 8.5% bodyfat. If cardiovascular health is your main concern, I guess whatever floats your boat but fat loss.....? Too much effort.

I just diet and hit gym 2-3 times a week. All this HIIT and all that is kinda redundant. You lose fat through dieting and minimalist hypertrophy training, not going crazy being a cardio bunny.

Can you keep it up? Ask yourself why people fail normally. Getting to a low bodyfat level is already difficult for most. MAINTAINING that low bodyfat level is even harder. Why? For most people:-
1. It's not fun.
2. They burn out because they depend way too much on cardio for bodyfat loss
3. Their diet sucks, they either go too aggressively low on a caloric deficit and cause a rebound weight gain or they think they can out train a bad diet.
4. They NEVER, ever, ever think long term. They just want to get in shape for some event, bla bla.