The phrase "becoming obsolete" is commonly used when referring to something that is no longer useful or relevant due to advancements in technology or changing societal attitudes. Synonyms for this phrase include "outdated," "antiquated," "archaic," "old-fashioned," "superannuated," and "falling out of use." Other similar phrases that convey the same meaning include "phasing out," "going out of style," and "losing relevance." These terms can be applied to anything from technology and fashion to language and cultural practices. As society continues to evolve, it's important to stay aware of what's becoming obsolete and adapt accordingly.