I have the similar issue with a Garmin, it had updates for life, but after an software update it no longer sees the USB port to be able to update any maps, although if I connect it to a Linux PC I can read & write files to it, but using a Windows PC or a Mac it's not detected. I think it's deliberate, but clearly cannot prove it.
I too got the email about my Tom Tom not being able to get new maps, apparently due to storage space to the internal memory. Life could have been made simpler by having a micro sd slot for that purpose but that is too easy. What it is all about is making money, if things were too reliable no one would need to upgrade. That goes with all things electrical and electronic. Lifetime downloads, lifetime guarantee, I may live to a 100 but the device will be lucky to see 3-5 years. I won`t buy a new Tom tom so they have snookered themselves really. Perhaps I`ll plug mine in to my Linux pc and give it a go.
My Tom Tom has been fine although 2 years out of date. It only came unstuck at the new junction at Bramton Hut recently but I just followed the others ! Mind you there have been times with the Tom Tom that have shown me driving along a field and not the road. We always carry a map anyway but it does get in the way of the windscreen ! When I think back though of driving in the past before sat navs it was never a problem. If I had route to drive I`d right it down before hand and refer to it as necessary. The problem is now that there because there is that much more traffic about and everyone is driving faster you hav`nt got time to think so you rely on the satnav. I still use the sun for directions !