All of this is admittedly easy for me to say, since I'm now a backseat raider. I do hope, however, that people aren't getting ultra-focused on hps as the sole indicator for a healer's efficacy.
From a design perspective, every class in a 25man raid should have weaknesses. If we didn't, then an argument could legitimately be made that there should be one class that we label 'healer'. And last I checked, resto shaman still have incredible strengths when the raid is able to stack. Admittedly, most fights don't always allow for that, but it doesn't remove that strength.
But putting that aside, aren't resto shaman still the only class with a Spirit Link Totem cd? It does nothing for your numbers but absolutely prevents raider death and helps achieve kills.
I'm also guessing that our heals still buff the absolute health of raiders, giving tanks extra breathing room and allowing us to heal players (even if they're already at full) when we know they're about to take extra damage so that all healers have an extra second or two to heal them up (even beyond what absorbs can carry) once that massive spike damage occurs. Again, this makes your individual hps lower, but prevents raider death.
And I know I'm biased on this, but when I was pugging earlier in this cycle, I was quite glad to be a healer with an interrupt with a short cd, given that I couldn't always count on others to have an interrupt available (or able to find their button). Heck, even in our 25man days, I remember jumping on interrupts when our interrupt folks were dead or unavailable. Since I recall the team now has approximately 48 rogues, there's probably less call for that now.

Now that HTT is baseline (and hitting 12 players is the same as Tranq and other similar cooldowns), we're basically going to get another talent on the healing tier for free!
Again, I recognize I haven't raided in several months and everything may be different now. But healers aren't their hps, and I'd think shaman still have a lot to add.