Use swfobject for Flash detection and you can provide all kinds of alternate content... simple text, images, links, .js slideshow, a mov or mp4 video just for the iPhone... ANYTHING this is regular HTML. Your imagination is the only limit.
And YES, HTML5 is a far cry from replicating Flash... so give them the best of both worlds.
Review this article which deals with Flash and SEO for more ideas:
If you think that Flash is somehow bad for SEO, it's time to dispell that MYTH!
If fact, in some circumstances I'll use Flash INSTEAD of just HTML because then I'll have better SEO than with just HTML alone.
The link to World Barefoot Center in the above post is just one example. View the source code and you see a couple paragraphs of text along with regular HTML links.... but what displays is the Flash version of the image and Flash links.
The client provided the artwork for the page... and that's what they wanted to use a .jpg image. Well yes, that could be done in HTML but it would be virtually invisible to Google. So Instead I converted the image into a Flash .swf and used swfobject to display the Flash. swfobject allows you to create alternate content inside the <div> which also holds the Flash .swf, then when the page is loaded it detects if the browser has the Flash pluggin. If it does, it displays just the Flash content, if not, it displays the alternate content. Since almost everyone has the Flash pluggin, for most people the Flash version of the <div> will display.
The alternate content for that <div> can be any regular HTML text, images, media player, links, etc., anything that you would use if you were not using the Flash. Now the best part is that the alternate content can be "over the top" as far as optimizing for SEO, since it will not be seen by most viewers.
Here's another example of SEO with Flash.. again, the page is just a single image provided by the client:
View the source code. The alt content is paragraph after paragraph of information about the site, including lists and links. If it was just the HTML, it might be kind of a boring Home page. But for SEO I can go "over the top" in promoting the site, since most viewers will never see that part... but it's all indexed by search engines. The end result is BETTER SEO using Flash than just HTML.
On another Web site, a Flash video is displayed, the alt content is the complete text narration of the video. Now how many people would take the time to read that if they could just watch the video instead?? again, better SEO with Flash than without. In fact in one case we had first page search result from that video narration within 4 hours of posting the page.
On still another site with a Flash video, the alt content is another video, but a .mov version, which will, in effect play Flash video on the iPhone (not possible you say??). Well since the iPhone does not have Flash pluggin, it simply displays the .mov version of the video, while everyione else sees the Flash version.
So anyway, if Flash is a part of your Web development, you should look into using swfobject and alternate content.
Eye for Video