How can Apple expect to sell the next model, if they make computers that last forever? Of course there is forced obsolescence. 100%. Not just computers - every product sold under a capitalist market has forced obsolescence. Just research pantihouse.
From what I can tell, you've had 1 or 2 free repairs, giving you a machine that is now 10 years old - but will die in the next couple years??
Try get 8-10 years out of a PC!! For a computer, even a Mac, 8 - 10 years is amazing. Assuming an average purchase price of say $2k, that's only $200/pa.
In this particular instance - and I'm not doing the research but people above indicated it's a known issue - sure, it seems there was a known problem that is going to reduce the computer's life. BUT -- 8 to 10 years? That's nothing to be sneezed at, even with a known problem!
Read any of my posts with regard to manufacture warranty, and consumer law, etc etc etc - I am ABSOLUTELY all for Apple being responsible for their products. 110%. When my eMac failed after 18 months due to bad capacitors, and Apple expected me to pay $900 to fix it - I was not happy. I spent 6 months telling every eMac Owner on the entirety of the internet to get on the phone to Apple, to make as many waves as possible, and in the end was even giving people Steve Jobs' email address (!), because in the end that was how I got a free repair.
BUT - that was for something that failed after 18 months. You had a free repair at 4 years from purchase - so that's good - Apple were acknowledging the problem. And another repair too?
If you're not happy, there's other options out there. Apple aren't really all that interested in Mac sales now anyways - it's just a blip in their income stream.