Another subtle consideration not touched on yet, is without their PFD, if the affected pilot is the PM, how are the v1 and rotate calls going to be conducted. The pilot flying will largely looking outside and likely be unaware of the failure affecting the other side and waiting for the usual calls. How does the PM communicate clearly the failure and the requirement for the PF to call/monitor the speeds for themselves. Or can the PM clearly see the other screen on a 777. Startle factor could also of course come into play. Sure sounds straight forward enough here on the ground to communicate the problem, but going down the runway at speed not so easy.
if the affected pilot is PF and it happens just before or during rotation, chances are neither pilot is going to notice 2 screens have failed until already airborne and climbing away. The PF at some point is going to have to hand over control. The urgency of this to happen I imagine depends on most likely the cloud base or visibility.
below 80kts, without the second screen how are you going to cross check the airspeed indications, so stopping should occur either way in that scenario.
Keep going
Doesn’t the 777 automatically call out V1 ? not a big deal even if it doesn’t the Pilot whose displays are operating can glance down and determine if VR has been reached