Paradoxically, it will not happen, unless they 360 on their design approach. With their current vision, all normal content will not have any single point of failure.
They have some fear of doing anything other than 3D no-scope dance/chessboard mechanics. However, Tender Valley has one trash pack with ticking damage. That must have been a "radical" design decision.
In Tender Valley on a perfect run as WAR I had more healing than WHM and the WHM had no hard-cast heals. When something goes wrong then the healer gets 2x tank healing if not more. All because as you mention - 90% of damage taken is in spikes from avoidable mechanics. They won't change existing content, it will be hard to move upcoming instances to be different but you never know. Depends on whether they are interested in feedback and take the correct one instead of dropping the issue with some healer-lock mechanic in the next savage. Still, if we get a more WoW-like design with constant damage we end up with the same problem - they don't want a single point of failure in normal content so the damage will be low enough to handle by non-healers

Maybe a new variant/criterion dungeon? That isn't obnoxious 3D chess mechanics, it has actual rewards, DF...?
Allegedly 8.0 is about jobs. Curious how much of this is true and what it will imply to their design decisions. AST is closer to WoW Mistweaver aggressive reactive healer than WHM and AST got a rework recently. Will they make healers more aggressive for more aggressive content? The bigger the change the more content will have to be altered and more work on actual design and balancing.