[Mailmunge] Future of ::Compat?

[postfix at ptld.com]

To clarify, is Mailmunge::Filter::Compat purely defang compatibility 
features that could go away in the future? Or does it also have features 
that are here to stay?

The mailmunge-filter.pl.example in 3.03 is using filter_begin(), 
filter() and filter_end() which i thought were being deprecated. Can we 
safely build on those subs without worrying about future compatibility?