Capacity is not directly connected to acceleration or top speed.Another is that the long distance version is not nearly as quick as the new Model S with nearly the same capacity.
I really hope that dual motors or ludicrous bring the acceleration to even compete with a BMW 340i let alone an M3.
Model 3 RWD could be motor limited. The motor is strong enough to do the 5.1 s -60mph, and reach 220mph. Or the 220mph could be software limited.
Also, with chemistry focused on COST above all, density next, choosing the bigger 2170 form factor (mostly for COST reasons), you're most likely going to see a lower maximum charge and discharge rate. So if an S/X 75kWh pack delivers say 300kW without over-zealous fuses and driving software, don't be surprised if the Model 3 75 pack tops out at 250kW or less.
Also, since it'all about cost, Standard and Long Range of course get the same rear motor. The standard cars use most of the power (slightly slower to 60mph), the Long Range eeks a bit more out by maxing the power the motor will take.
I have some hopes for future Performance versions. Cells could get totally different chemistry to enable higher power output. To get truly faster acceleration from dual motors, that may be needed. And we can dream P will come with the standard range cars, but of course it will not.