basically what needs to be done is that Apple, or a third party, makes an adapter that goes from Thunderbolt to MiniDisplay Port, disableing the PCI-E function inside the Thunderbolt cable, so only the Monitor part can come true, without bugging. This way we can buy the Thunderbolt Display, hook it up to our old MacBook Pro's and when our laptops fail or die, we can replace them and as a reward get all the functions the display has to offer with Thunderbolt.
Why is this so difficult Apple? Is it not clear hundreds of people are having complications with your monitor? Sell the old display, place is out of stock, and go on selling ónly your new display, and let people know that the thunderbolt options (USB, Ethernet etc) won't work withouth a Thunderbolt Mac (OBVIOUSLY) and we will all understand, buy the display anyway, and soon upgrade to a new Mac model.
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Anyway. Please, if somebody here finds a way, by using an adapter of some sort (and I'm sure it must excist)!!! let us know. Or if you are good with electronics. make Thunderbolt - MiniDisplay Port and become our hero.