AT rifles are very useful for our current armour level, delivering enough penetration for low cost. For example, the Panzerbüchse 39 could've penetrated the projected frontal armour of our new tank up to 300m [1]. They were effective later in the war, though only in some specific situations [2]. At the same time, the high muzzle velocities and accuracy makes them usable as sniper (or, for the newer term, anti-materiel) rifles. They lack the higher signature of RPGs (no smoketrail), and hit easier.
Of course, penetration capabilities are limited due to the limit on the calibre.
Then again, the cost is pretty low - while for an RPG, you mostly pay for the rockets which are expensive, an anti-tank rifle just uses quite inexpensive bullets, though the rifle itself is usually more expensive than the RPG launcher.
Edit: Note that we already kind of have an anti-tank rifle (though not that effective) in the 15mm MG.
On the tank role: Before WW2, the tanks roles as defined in Great Britain were cruiser and infantry tanks, with the cruisers being quick but comparatively lightly armoured and the infantry tanks just fast enough to keep up with infantry and therefore heavily armoured and armed.
I myself like a mix of the two, meaning we concentrate on just one type of tank (easing supplies), comparatively focused on speed but not losing too much of armour or armament. I think we should aim at a speed of about 40km/h, adding armour and armament as necessary and allowed for by the engine. Sure, if it can do 50 but can kill enemy tanks reliably, I won't worry, just like if it only does thirty but that's needed for anything but a non-paper-thick armour. That's another thing the tank proposal does: Giving us, the players, experience in tank designs and performances.
There's no update today, so you take your time.
Might be useful to define your 'today'
GMT+1?
[1] Wiki gives it as 2.5cm at 300m
[2] See Pavlov's House, for example.