HTML element content models vs. components

Expanding on the general web component discussion, one area that hasn't been
touched on AFAIK is how components fit within the content model of HTML
elements.
Take for example a list (
http://www.whatwg.org/specs/web-apps/current-work/multipage/grouping-content.html#the-ul-element
):

<ol> and <ul> have "Zero or more <li> elements" as content model, while <li>
is specified to only be usable within <ol>, <ul> and <menu>.

Now it is not inconceivable that someone would like to create a component
<x-li> that acts as a list item, but expands on it. In order to allow this,
the content model for <ol>, <ul>, <menu> would need to be changed to
accomodate this. I can see this happening in a few ways:


A.) allow elements derived from a certain element to always take their place
within element content models.

In this case, only components whose host element is derived from <li> would
be allowed within <ol>, <ul>, <menu>, whether or not it is rendered (q.v.
the "Should the shadow host element be rendered?" thread on this ML).


B.) allow all components within all elements.

While quite broad, this may be necessary in case the host element isn't
rendered and perhaps derivation isn't used. Presumably the shadow DOM in
this case contains one - or even several - <li> elements as topmost elements
in the tree.


C.) Just don't allow components to be used in places that have a special
content model.


Thoughts?

- Roland