Joseph Wright wrote:
> 
> \latexstart
> 
> \loadclass{article}
> 
> \loadmodule{whatever-module}
> 
> \documentstart
> 
> Some text
> 
> \itemizestart
>   \item An item
>   \item Another one
> \itemizeend
> 
> \documentend
> 
> \latexend

Looking back over this, I suspect that the current LaTeX model is pretty
good at the user level.  Of course, there will be a need to
differentiate LaTeX3 and LaTeX2e documents, but I guess \NeedsTeXFormat
should work fine there.  So the structure:

\NeedsTeXFormat{LaTeX3}
\documentclass{article} % Loads something like article.cls3
                        % or article.ltx3.cls
\usepackage{whatever} % Perhaps \usemodule or \loadmodule better?
                      % Perhaps .mod extension rather than .sty,
                      % or perhaps whatever.ltx3.sty?
\begin{document}
Some text
\begin{some-env}
  Text
\end{some-env}
\emph{With emphasis} or not.
\end{document}

still looks like the best plan to me.  Of course, that leaves a lot of
other questions, but you have to start somewhere.
--
Joseph Wright