Generally I think this is a wrong measurement.
Now it is a mid-range phone and counting begins now or right after delivery (soon). Not next year or in two years. So support/lifetime begins (now) and hopefully will last some about five years.
It was the same game with FP2. Mine was from January 2016 now lasting 3,5 years already and it looks quite positive for it atm.
Support/lifetime began in fall 2015 where the first batch was delivered.
But again there were customers who bought it last year - where it already was close to its eol.
Support still goes on, but counting a five year lifetime from now does not meet the realistic conditions how the marked works. Fairphone could manage to save FP2 spare parts for a few more years, but this actually is unusual imho. For many mainstream manufacturers/products when having reached the eol there are no spare parts and if your “newly” purchased phone has serious troubles needing spare parts most sure you will be out of luck. The dealer cannot help you although you “just” purchased the phone which is in the market for some years. He can return it to the manufacturer just to face the fact that there are no spare parts anymore. So your option for “repair” whilst the 2 years of warranty is a full replace.
Other fields in the electronic market work similar such as e.g. tv sets.
If you expect it to last 3-5 years, now would be the best time for your purchase in consideration for available spare parts. Any time later can bear the risk of (most common) spare parts being unavailable keeping you with a broken/unusable device which may not have reached the ~5 year lifespan.
Do you think here of how high the repair costs would be in comparison to the phones value?
I always try to get things fixed even though they are not of value for others, but for me.
Partially I do agree.
But who knows if there are so many FP2 hitting EOL in 2020 Q3, afaik there is no kill-switch implemented. 
I am pretty sure the majority could run for much longer - but often it’s rather an individual decision of users “wanting” to have something new.
Not every user, including me, is doing security critical things such as online-banking. For us it’s a device for simply phoning, surfing the net, multimedia and some chatting.
And I can remember users here who managed to break their phone within a few days after delivery. So how can a manufacturer know when it is the right time to launch a new product?
Again I can read here often that the price of the FP3 is too high. And this without 5G.
Other mobiles offering 5G are often twice as much.
I believe Fairphone also tries to stay within a price range so many potential customers can afford it. I guess that is mandatory if they want to move further into the market.
At the end they have to trade-off what to include and what has to be sacrificed to keep a limit and stay attractive.
