Ashley Many thanks for the response, but I think I wasn't clear with my questions.
I mentioned C4 as a small joke, not as an expectation or the discussion, but my original question is very important to me. My main concern is, and lets be realistic here as we all don't know what the future holds:
Lets fast forward a random amount of years, e.g. 5 years. Lets say for whatever reason:
Scirra makes a new product and ends C3 and the new product doesn't load some aspect of c3p files therefore rendering c3p files unusable. Or maybe Scirra doesn't receive payments and must shut down, there's many possibilites, positive or negative (I wish for great things for Scirra, of course!) whatever the reason, the main point is that C3 becomes inaccessible and the verification servers are inactive. Let me stress, I'm not suggesting there's going to be a new product, and I'm not thinking Scirra is going downhill, but please follow the hypothetical situation.
So my concern is, that I cannot find in the terms and conditions that there is a legal requirement that Scirra will provide a solution to opening c3p files if Scirra must retire C3 for whatever reason.
Whereas right now, we can open Construct Classic CAP files indefinitely, and Construct 2 CAPX files indefinitely, as long as we have the installer (and licence key file for Construct 2).
So, 5 years pass, C3 is down and the verification servers are offline. Now: the person I was talking to that uses Construct 2, they would had continued to use a very dated C2 which can be potentially maintained by custom builds and downloading NodeWebkit updates. C2 will always generate the HTML5 code in the end, plugins can still be made indefinitely to expand C2.
This means they would have spent about £70 one-time, and they will confidently know that they can open their .capx files indefinitely, even in 30 years time if they kept their capx files. All the source code is previewable/buildable so long as they keep an installer of C2 and the licence key file.
Compare that to me, who would have have either paid monthly (£839 for 5 years) or yearly (£424 for 5 years). And without the legal requirement that Scirra will provide a way to open c3p files, then Scirra "could" simply close the Construct 3 website down, close the verification servers, and there would be no way to locally open, build, or edit our source code (our c3p files).
I'm sure a third-party individual would try and find a way to preserve the offline version of C3, but would we seriously be expected to rely on this after spending the above money over the years (and that's only 5 years, imagine more), simply to have a risk of having all those years of work just locked away?
I still have my KickNPlay (released in 1994) games from when I was young, and personally these are very sentimental, so long as I keep backups of the installer and game, I can still find a way to view them if I wish even after 25+ years. But with C3, I'd be extremely ticked off if I lost even 5 years of real game development work (which may need to be maintained, updating old games, etc.) simply because there was no legally binding reason for Scirra to release a solution to open c3p files.
I am not complaining about the subscription model, I must clarify, the cost is absolutely fine, and I'm not asking for an offline way to read/edit c3p files whilst C3's verification servers are active (although an downloadable Offline "Construct 3 Player" with event sheet view stripped out and only preview mode available would be great for archival/preservation reasons).