Visual modifications have been confirmed on several occasions and are being implemented in one of the very next patches following the release of 2.2 - not including possible minor bug-fixing patches.
Following the establishment of a largely-autonomous English Management Team, individuals belonging to the English Community have been - and will increasingly be - included in the very development of Tanktastic; with all that obviously implies - though, of course, it's going to be a gradual process.
Early development designs, as of now, call for visual modifications to be implemented alongside major changes in the tech trees and unit-development/upgrade mechanics.
As a sneak peek, in accordance with early agreed development plans in this sense, these new mechanics will revolve around basic platforms you may upgrade into a variety of different AFVs by adding and removing modules and by unlocking "blueprints". These changes will follow upcoming changes to armor profile and mechanics concerning projectile performances.
That said, however, it will be highly simplied so to avoid unecessary confusion and to ensure the arcade aspect of the game is fully preserved. Modules will also be shared with other platforms, thus easing grinding.
For instance, one of said platforms will be the basic Leopard 2A0. Modules will include a variety of improvements based on real life military hardware, including projectiles and APS systems. You will start off with a basic I+ gen APDS round, i.e. the DM23, capable of defeating I gen. ERA; you will then be able to upgrade to a II gen. APDS, the DM33. And so on.
As the DM23 was used by the IDF as well, this "module" will thus be unlocked for some Israeli tanks in turn.
Once all modules for a particular "blueprint" have been unlocked and mounted, your tank will turn into that "blueprint": a Leopard 2A1. And so on, up until the MBT Revolution.
Once you have earned enough "development points" on any given platforms, you may unlock the following one. In this case, either the Leopard 2A5 - which will take you up to the Leopard 2A7-140 - or, possibly, the Main Ground Combat System Platform armed with newest Rheinmetall 130mm L/51.
Another example, as regards the Armata platform, you will be able to unlock "blueprints" and buy modules to get a variety of AFVs, from the T-14 and the T-15 IFV to the 2S35 SPG.