A hydrokinetic torque coupling device features a casing including an impeller shell, a casing shell, and an intermediate casing component connecting the impeller and casing shells. The intermediate casing component includes a casing wall portion and a piston engagement portion extending inward from and being non-rotatable relative to the casing wall portion. The device further features an impeller including the impeller shell. The turbine-piston is coaxially aligned with and hydrodynamically drivable by the impeller, and includes a turbine-piston shell having a turbine-piston flange with an engagement surface that is movable axially toward and away from an engagement surface of the piston engagement portion to position the hydrokinetic torque coupling device respectively into and out of a lockup mode.