Your logic is flawed
If someone does not play as much, it can be an indicator of a lot of things...not being content with the offers one of it. So, most likely, if the offer is changed (like a better f2p system, better access to play with friends again, additional stuff in lower tiers etc.) these players might play more again.
On the other hand, if you have a limited rl time to play, the offer better has to be good to be worth even the 85 pounds. And you are not one to judge, what people consider worth to buy or not
With the actual f2p model you must also add a "worth to play" factor.
Of course, if you wait too long with welcomed changes, these players might not even recognize or be not content with them...just because they do not care anymore, left or have reached such a high expectation level or they combine too much bad emotions with the game, that what might have brought them back after 1 year is not enough to bring them back after 2 years.
Trying to win f2p as customers without forcing them to sub, should be a goal...not treating them like cost factors or second class (which they are not...plenty of valid arguments for that around).