Looks like I will still see them 5 times this year despite them missing RIAT.

7 Ship will continue until 2030

https://uk.news.yahoo.com/red-arrows-fly-just-seven-170600220.html

Old Engines  

The BAE Hawk T1 has a slightly modifed RR Adour engine which gave better performance for aerobatic manoeuvres over the standard engine, or at least I think I read that somewhere,yonks ago.

The more modern versions use the  Rolls-Royce Turbomeca Adour Mk. 951 turbofan, I would have thought the remaining  Reds aircraft could be upgraded.

Sky News maybe talking out of their Daily Mail, if you get my drift.

It appears to be a bit more than engine spares, it's a shortage of airframes which makes a bit more sense.
I believe there are some Hawk T1's in storage at or near RAF Shawbury in the midlands.

More here from BBC News website...   https://www.bbc.co.uk/news/articles/cj9p8rvl0d0o