Despite all the ranting and raving I might be (or am?) known for about the performance and export options of Construct post-Classic, I actually agree with this thread.
Construct 3 is known to be an editor-only change, since it was specified as using the same runtime as Construct 2. Considering plugins in Construct 3 (as well as the whole engine, and now editor) are all JavaScript, it effectively means the whole thing is possible to port forwards and backwards to C2 or C3 anyway.
The cloud services, and potential for a Google Docs-like real-time collaboration system, is what could be really powerful, in addition to the added control over the interface that plugins have (because it's in a canvas already).
Selling those services as a subscription "Construct Cloud Services", and maybe even giving priority/premium support to users of that (since Scirra can literally download and run/check out the projects stored on those cloud servers, assuming the client allows it) would be a professional service sold at a professional price.
Otherwise, I don't see it being a long time before other engines do "what C2 does" and have the added benefit of native export to:
PC (Win/MacOSX/Linux)
Consoles (Xbox One, PS4, Switch, WiiU, New Nintendo 3DS, PS Vita)
Mobile (Android/iOS)
On top of WebGL export, which is the only one Construct actually "has" (without wrappers)