The USA is embarking upon a further upgrade of the M1 Abrams series, the M1A2 SEP v.3, with the SEP v.4 to follow in the 2020’s. Russia has unveiled the T-14 Armata, a main battle tank that will be accompanied by a series of other armored vehicles built on the same platform.
Israel has been working on a successor to its Merkava series tanks for some time.
Here’s a video simulation, showing what it calls the Carmel tank project. It’s still a concept, and doesn’t even exist in prototype form yet, but shows how that country is thinking about the future of main battle tanks and armored fighting vehicles. It’s rather different to US and Russian thinking on the subject.