Chris,
You really can't imagine that in in 15 years there will be a better router?
Your expectations from Festool is that they'll still be churning out OF1400s?
How's your '93 vehicle doing? since you certainly must still own it. Sorry, i'm not picking on you, I'm trying to make a point (actually my own '74 is doing fine, but it's hardly a practical work vehicle)
I just sold my old model Kreg pocket hole jig and brought the new one. the old one cost me about $30 (that's not what I PAID for it, it's what it cost me) the new one I have no idea yet of it's cost, my investment has been $140.
Did the old one still work fine? sure, did a great job,
Is the new one better, yes, I love the front clamp and the dust control is well worth the price alone. But the real test of the tool is whether it's a sound investment. In the case of the Kreg (I'm using this example since you mentioned you own one) The front clamp is just convenient (that's for my personal comfort, not a hard business decision), but the dust control means I can make pocket holes inside a customers home, now that trim piece can be cut and fitted quickly on site, Now tidy toe-kicks can be cut to fit someone's sloping floor and pocket holed on site, that will only maybe save me an hour every two weeks - now never mind the business cost of that hour or my hourly rate, the point is also that I only have so many hours in a week (and at my age, I only have so many hours left total - but thankfully we don't haver that information at our fingertips)
So the replacement is a given, the investment is a sound one, and at some point that new one will be re-sold to someone at a discounted price and reveal the true cost of this tool.
A tool is not an heirloom, it's not something you buy to pass on to your grandchildren - even if it's a fine Lie-Nielsen plane don't buy it for your grandchildren, first and foremost buy it because it's a great tool and worth the investment, if you still own it when the inheritance is worked out and the grandkids want it - you've either been a great grandfather or they're planning on selling it (in which case in my humble opinion you've failed as a grandparent).