We know they'll be antisystem, not damage units. So it seems to me that they'll be very vulnerable to pure DPS units without backup. We also don't know if they'll be able to travel between gravity wells yet. (though probably), how much theyll cost, and how much research it'll take to build them or make them effective.

I'm not too concerned about a Corvette rush.

The "original scout rush" had nothing to do with defeating your enemy with a swarm of scouts.  It centered around 2 things:

1) Destroying enemy "ghosts" with scouts.  Back when the enemy building placements were visible before he began building them, they had I believe 1 HP (could be even 0) and could be destroyed by a sneeze making your opponent lose full money for the building. I still feel guilty about the time I made my opponent waste 750 credits placing a single extractor

2) Scouts would destroy construction frigates, which had no shields and did not regenerate hull. Thus making your enemy unable to tech up, build repair, or even build second frigate factory so they just become overwhelmed by 2 factory cobalt spam.

Attacking with scouts as an offensive force was infant second wave of scout rushing, and took grip much later.

But it is too early to speculate on what you are referring to.  Like others said the cost of the frigates and their stats may make this not practical.  For all we know they will have 4 dps. More likely they will be units that mess with stuff like shields, regeneration, targeting and weapons, or engines.

Yep, #2 rush is still quasi viable of course   Thats why on close maps people got into a habbit of building second frig factory fromt he start hehehehe.

Wonder if it will be like this.....