The runtime is the same as Construct 2 for now and the foreseeable future (HTML5), so if you are happily using Construct 2 right now, then you'll be able to continue enjoying that with Construct 3, with a paid subscription fee per year.
So yes, they're being pretty up-front and trustworthy, eg: they're not promising "Switch and Nintendo 3DS export!" or "Xbox One and PS4 self publishing!", or anything too crazy to actually expect decent outcomes from using HTML5 (although WiiU doesn't support WebGL, and it should be stressed how big of an impact that makes on scope of games capable on the console). So export-wise, they're pretty clear that it's web-based.
All the third party exporters and plugins aren't made by them, so they can't promise that it'll work 100% of the time, and since that's their demarcation point then it's just a matter of whether each user personally wants to take the risk on using an exporter. As long as the risk is made clear before purchase, that could be considered fair and, again, trustworthy!