I’m not bringing it back but you can achieve the same by defining
a new typeface/family and refer to a certain alternative of this
typeface with the \classfont command.
\definefontfamily[keywords][ss][DejaVu Sans Mono]
\definefont[kword][\classfont{keywords}{Sans} at 13pt]
\definehighlight[keyword][style=kword]
\starttext
Text font \keyword{keyword font}
\stoptext
Bug: I prefer Euler font for math. This does not seem to work with the latest fonts interface.
The name of the font is “Neo Euler”:
\definefontfamily[mainface][rm][TeX Gyre Pagella]
\definefontfamily[mainface][mm][Neo Euler]
\setupbodyfont[mainface]
\starttext
Text font $math font$
\stoptext
You can also use the predefined typescript which has the name “eulernova”:
\definefontfamily[mainface][rm][TeX Gyre Pagella]
\definefontfamily[mainface][mm][eulernova]
\setupbodyfont[mainface]
\starttext
Text font $math font$
\stoptext
Wolfgang