Como dizer "Cair em desuso" em inglês

Dependendo do contexto ...

Obsolete: no longer used because sth new has been invented

With technological changes many traditional skills have become obsolete.

Out of date: Out of style or use
These figures are very out of date.
Suddenly she felt old and out of date.
an out-of-date map
out-of-date technology

Old-fashioned:(sometimes disapproving)
not modern; no longer fashionable, dated

old-fashioned clothes/ styles/ methods/ equipment

Out-dated: no longer useful because of being old-fashioned
outdated equipment
These figures are now outdated.
It is an outdated and inefficient system.


Oxford Advanced Learner's Dictionary/The Free Dictionary

To fall out of favo(u)r

This style of house has fallen out of favor with most people lately. The Free Dictionary

And there is "to fall into/in disuse" in English as well:

These are words (or meanings) falling into disuse.

Regards