I think the Abrams' case is bit too extream. There is not a single tank in the world that has enough armour to be safe. Hizbullah blew up IDF Merkavas and these are not bad tanks. Why waste money on super tanks when a round from Carl-Gustav or some bit more expentsive missile can blow it up(but much cheaper then a tank), not to mention a A-10 or anything similar to it.
I know estonian small forces in iraq don't even like to use APCs on patrols, but prefer bit extra-armoured trucks. The APCs they say, are more deadly. It's how the forces effect the machine when a missile hits.
And as I said even Hizbullah was capable of blowing up world class tanks, not to mention someone like Iran or China.
Tanks are getting bit out of date. They were needed in WW1 to cover the attacks cause defensive weapondry was so much better then offensive. In WW2 they were also very good offensive weapondry, but I really can't understand what's there so much to do with them nowdays. All they do is blow up rebel buildings or suspicious cars on Iraqi highways....