Macromedia/Adobe got/gets designers, and too many people don't realise that.
Even assuming this is entirely correct, Adobe is planning to produce authoring tools for HTML5 directly. As for existing content...
You may not be interested in it, but there are some gems buried in NewGrounds along with all the crap.
NewGrounds is hardly the reason Flash won't die. If it was just Newgrounds, well, hey, there are some gems buried in platform-specific native game binaries -- and not all of these are Windows, mind you, there are some real gems which ran on Mac OS 9. It's an issue, but it's not a point against moving forward to a viable replacement -- especially something like HTML, which is going to be a hello f a lot more future-proof than Flash.
Flash will die, and this kind of creative content will die with it until a new challenger appears; or more likely, Flash will just refuse to dies, and the geek elite just won't understand why.
So, of this, option one is a lot more likely. Flash refuses to die right now largely because of video, and it's being steadily replaced there. There are a few niche places where Flash can still do things HTML5 can't -- right now, audio strikes me as most likely, and even that is being addressed -- but it will eventually die.
In the mean time...
None of the other solutions are accessible to designer types the way Flash is.
If you're more than a one-man Newgrounds operation, it doesn't actually matter that much. You know what designers are good at? Designing. There's a reason Flash has a reputation for being slow and buggy as hell, a constant CPU drain, etc. Some of this is Flash's own fault, I'm sure, and I can back this up by comparing YouTube's performance with Flash versus any native player on the same video file. Most of it is enabling designers to attempt to program, with similar results to enabling executives to attempt to program in Excel.
The same tools will eventually come to HTML5, and I'm alright with that. Please don't take this as an elitist stance of, "Leave programming to the professionals." All I'm saying is that if the existing stuff isn't accessible to you, some of that is because it's overly complex, but a lot of it is because you aren't a programmer. There's no reason you couldn't be, and many designers do make that leap (or simply team up with a programmer). But you do have to invest some time in learning something about how computers actually think.
To put it another way, I don't think I would be taken seriously if I attempted to do serious design work with MS Paint. There are tools which let me easily throw together a comic, but I don't think this compares with this or this. These aren't the best examples of either, but honestly, if the ragecomics went up in smoke, I really couldn't care. That's kind of how I feel about Flash, especially when it's used by designers.
If you're neither willing to learn some real programming or work with a real programmer, then I'm not sure I will miss the loss of your content. If you are willing to do either, then I have to imagine that Flash vs HTML5 isn't a huge issue.