Modern tank lasting time? (valid for other modern systems)

[Mohoender]

Originally Posted by Legbreaker

The milage problem is one all modern tanks face. Weighing in around and average of 50-60 tonnes they're all going to chew through the fuel and from that viewpoint alone, only the wealthier, more developed countries are ever likely to employ them.

Going away from the original thread, I have a question. Wouldn't modern tank quickly become useless simply because of their weight? In a modern world, the 50-60 tons are definitely not a problem but with decaying bridges and rusting infrastructures everywhere, wouldn't they be stopped by every small river around?

After a few years of the twilight war, I don't really expect many bridges to be still capable of resisting such heavy weights.

Another question. How many time can last a M1A2 Abrams (even worse: a french Leclerc) without proper care and the vast technological support system to fix them?

Similar questions can concern fly-by-wire aircrafts.