I'm of the opinion that something needs to change. As-is, Viper suffers from a general design problem that has existed even before 7.0, but until now no other class has been held back by it nearly as much. Twinblood/Twinfang don't just encourage double weaving, it's essentially a mandatory part of the rotation. The problem? Unless you have a low-latency connection, you can't double-weave without clipping your GCDs, and should you clip your GCDs, your DPS drops and your rotation drifts, likely causing misalignment of burst phases with party buffs as longer fights drag on. Bottom line: No amount of skill can overcome a problem brought on by a combination of game client limitations and connection latency.

The double-weaving problem isn't something new, of course, and from my understanding of how it impacted classes prior to 7.0, you could overcome the problem to some degree with adjustments in rotation to avoid double-weaving at a small cost to DPS and/or adjust gear SkS/SpS to achieve a higher than BiS speed to be compatible with your specific connection conditions. From what I understand, this resulted in either a nearly-neutral or only minor change in theoretical DPS. At the very least, you could play a class affected by this and still be viable in high-end encounters.

I'm doubting the viability of Viper under the same conditions. You can't currently decide to use other GCDs between twinblood/twinfang in order to avoid clipping your GCD, and dropping either of those will result in a fairly obvious DPS drop. I do realize that hunger's/swiftskin's coil both are 3.0 GCDs instead of 2.5 which helps in making double-weaving viable to more players on its own, but there's a problem: Swiftscaled. Even with no investment in SkS, Swiftscaled alone brings these to 2.55 seconds, and given that double-weaving can be problematic on RDM even without investment in SpS at around 2.5, I doubt that extra 0.05 seconds will mean anything, especially since given how gearing works, you probably won't be able to completely avoid SkS on viper and will have real speeds that are quicker (with just basic level 80 gear from the unlock quest and level 80 poetics accessories, I hit 2.51 with these).

Just to verify this was still a problem with 7.0, I moved a character over to OCE and, yeah, it's bad. The first attempt I made just barely didn't clip the GCD as far as I can tell, but as I repeated attempts, I kept clipping. I then realized it's due to the fact that the first attempt was without the Swiftscaled buff. Basically, once you get that buff, you'll clip GCD each time you go through the combo that refreshes the buff. As far as I can tell, this forces you to choose between the lesser of three evils:

* Drop either twinblood/twinfang (simple loss of 300 potency every 40 seconds)
* Allow the GCD to clip and do the rotation otherwise as normal (DPS loss depends on exact latency)
* Allow both Swiftscaled and hunger's instinct drop off before using Dreadwinder to rebuff them (likely a near-fixed DPS loss, but without running exact numbers I'm not sure if this is better or worse than the first option)

The double-weaving problem is nothing new, of course, it's just so obvious with Viper that it feels like something needs to change. That said, when I play this class on an NA world with my current connection, it seems fun, and I could get the hang of the positionals with practice. I totally get the reasoning behind most of the "Don't change Viper" sentiment, but I wouldn't be surprised if SE plans to address this specific concern. In terms of what they can do, I see 4 reasonably viable options:

1. Rework Swiftscaled into something else so that it isn't reducing GCD by 15%. Without that, the double-weaving is possible even playing across an ocean as I learned tonight.
2. Combine twinblood/twinfang into a single skill (combine the potency as well). This removes the obvious mandatory double-weaving in the rotation while leaving the balance of the class unchanged. This seems so simple of a change that it wouldn't surprise me that this is what SE will do even though I bet very few actually wants this.
3. Increase the 3.0 GCDs to something like 3.5 or even 4.0. This will require other adjustments to maintain the class balance but will make double-weaving more possible for more people (at least this specific instance of it). Of course, for people with fast connections, you get a small burst of buttons followed by a 1-1.5 second snooze before doing it again. I doubt this would feel good even if it is otherwise largely maintaining the current rotation.
4. Enhance the game client to make double weaving fully supported. I believe I've read about mods that effectively removed some/all of the mandatory timers the game client has to allow double-weaving on high-latency connections, but that doing so (in extremes) could allow players to do things that wouldn't be possible and could get them banned. An enhancement along these lines would likely fix the problem without needing a change to rotation for players who like it as it is while also throwing a bone to anyone who plays any other class with any number of double-weaving possibilities. This is the option I'd hope SE would actually take as it's all upsides and no downsides as far as I can tell, but I'm not optimistic about the odds they'll actually go this route given their history.

Basically, option 4 would allow fixing Viper without actually changing it and help other players/classes to boot. Too bad the odds aren't great they'll actually do that, though.