the problem with that article is that there is no "Valley of Death" between the Astutes and the Dreadnought SSBN's
The first SSBN was commenced 7 years ago and steel has been cut on 3 of the 4 planned boats
Agincourt - the last of the ordered SSN's - is planned to enter service "in 2026" - after an 8 year (I know, I know) build.
I can't see there is a "start-stop" in fact I suspect the SSBN's are being delayed due to the time it takes to complete the last two SSN's
To build two more Astutes for Australia would extend the SSN programme by 16 years out and selling two "off the shelf" would reduce the RN SSN fleet to 5 for that period as the Trafalgar's are already 30 years old and in desperate need of replacement.