Except that instead of having a .908ish guy who's proven that he can take a heavy workload, now they have a .908ish replacement that hasn't seen full-time duty in a long time. Even if they platoon him, the other guy is not as good as Cam Ward.
There's also the "playing in front of the #1 gives the boys confidence" trust argument, but it's a harder sell.
Either way, they're not as good minus Cam Ward IMO. Enough to suddenly choke away the division? To the Caps? Who knows.
Ellis has been .920+ this season. I'd expect him to regress with a bigger workload, but the overall point is that to the extent that they can ride Ellis, they're likely as good or better than they were before. If they're forced to rely on Peters much then that is where they'd be in trouble.