This discussion arose in https://core.trac.wordpress.org/ticket/47183 and while that ticket was about getting rid of an error message, I raised some points which are better discussed here.
references to eot and ttf can be removed altogether. There are some tickets where authors are trying to remove references to IE such as IE specific css files etc, which helps in ease in maintenance.
Zach Leat has argued here why css @font-face declarations need only have references to woff2 and woff files:
This discussion arose in https://core.trac.wordpress.org/ticket/47183 and while that ticket was about getting rid of an error message, I raised some points which are better discussed here.
references to eot and ttf can be removed altogether. There are some tickets where authors are trying to remove references to IE such as IE specific css files etc, which helps in ease in maintenance.
Zach Leat has argued here why css @font-face declarations need only have references to woff2 and woff files:
https://calendar.perfplanet.com/2016/no-font-face-bulletproof-syntax/
Also, he has argued that it's better to have references to woff2 and woff files rather than using data-uri in css as base64 encodes:
https://www.zachleat.com/web/web-font-data-uris/
So I suggest making woff2 and woff files for dashicons and declaring references to them in the css files.