The hospitalisation numbers are manageable but have basically removed all the opportunities to catch up on elective surgery etc. Staff redeployment has basically closed all the non-urgent care stuff from physio to mental health.
They're also putting a lot of stress on intensive care staff, and some of the internal medicine specialties. Asking people not to take holidays, or to do extra overtime, for a few months is one thing - to keep asking for it 18 months later and with seemingly no end in sight is a different kind of problem. The emotional and physical strain is showing. A&E departments and the ambulance service are having to deal with more work than they should and covid wards are heavy on staff and space. Hospitals are struggling to discharge patients because things like care plans can't be created and residential and community care don't want potentially infectious people being transferred to them, even if they don't need further hospital care.
That said, the statistical models said this was coming. In fact the main ones suggested that hospitalisations could be twice as high by now. Those models generally showed higher but narrower peaks than we're experiencing. The total numbers, deaths/hospitalisations, are as predicted but they're happening as a near flat line. We have indeed flattened the curve but at a level that's been continuously hard on staff for months.
You're right in general terms though. The case rates are as expected, the death rates are not racing away, hospitalisations are high but less than a quarter of the previous peak. Sustainable? No, according to the front line staff handling it or the people who are being kept waiting for medical attention. Yes, according to raw bed counts.
At any rate Javid was right about one thing. We are utterly dependant on the vaccines keeping working, the rollout continuing and the boosters doing what we hope. The booking system website updated last night to stop telling the 6 month+ group to wait until their GP calls and to allow them to book boosters directly, so maybe things will start to speed up.
TLDR - case rates are high but don't take them as the key indicator, they won't fall much until enough under 18s have been vaxxed or been infected. Deaths and hospitalisations are both in line with the most optimistic models the government is using, and may fall quite quickly if the booster program works.