WOTC has quietly launched print-on-demand old-school D&D modules. You can now get many 1e and B/X modules freshly printed! I’m sure many more are on the way.
Castle Amber is one example. You can now get a new copy of this classic module on print on demand at DM’s Guild. Add in the 5e conversion guide for Castle Amber and you’re all set to run this adventure in 5e!.
Combine the classic adventure modules with the Classic Modules Today conversion guides (see http://classicmodulestoday.com/modules-conversion-list/ and http://www.dmsguild.com/browse.php?keywords=Classic+Modules+Today) and you’ve got some really amazing old school adventure support for D&D 5e.