Just some suggestions...
1. Easy Image Gallery admin upload and front-end display (based on SIG Pro plugin in K2)
Not quite as elegant, but you could use any gallery plugin that works with joomla on a flexicontent text field (you'll need to enable the plugin in the field). Galleries that have both a component and plugin will have their own user friendly way of uploading/resizing the images. The admin just needs to note the "gallery ID" and enter it in the right Flexi text field. So the only difference is you have to go to two places instead of one.
2. Video upload and display with several cool options (local vid upload, grab from online provider using ID, or grab from server using URL, etc). The video playback is based on AllVideos in K2.
How about trying AllVideos Reloaded. It's a fork that has a component for easily uploading videos and selecting youtube and what not. Then like above, you can then use a "text" field type in Flexicontent (don't forget to enable the Allvideos plugin on it). The admin just needs to enter the name of the file.
3. K2 Tools Module - can create several different content modules instances from one tool (archive, menu, search, tag cloud, breadcrumbs, dropdown select menu).
Most of these things you can do right now! Flexicontent can use most of the native Joomla modules. (although some like the latest news will produce non-SEF links). There is a tags module... check the downloads.
4. K2 Content Module - can create modules to display content in several ways (random, newest, most popular, category, specific item, by tag, oldest, most recent, alphabetical, ID, rating, featured, non-featured etc).
This is what I think the new module is going to be about... although I can't say I'm sure. Again the core modules work for a lot of this, but not without URL problems. For now, maybe try the "placehere" module or "ultimate Content display" (Joomlaworks) and see how it works.