"Use it or lose it" isn't a principle we generally associate with ownership — we all have closets filled with unused stuff that nevertheless remains ours for years — but it is one of the hallmarks of trademark law. Whatever your opinion of our current IP laws, it's almost unquestionably a good thing that individuals and companies can file for a trademark only to sit on it, not unlike those domain squatters eyeing an opportunity to capitalize not on a fully-formed idea, but rather happening upon a name likely to be sought out for use. Conversely, there's always the chance that the one messing up your chance at a trademark is yourself.
Such is the case for AXA Equitable Life Insurance Company, which has at present lost its ability to use the term "Equitable" that it held a mark on for over 150 years after a Utah federal court injunction. The court found that AXA lost the ability to continue its use of the mark in its bid to rebrand to "Equitable Financial"; this coming after a previous rebranding to simply AXA from 2014-2017, dropping "Equitable" from the name. Now the move to return to "Equitable" is blocked by what the court determined to be the potential for confusion with the Equitable Life & Casualty Insurance Company.
As laid out in Bloomberg Law, the court was unswayed by argument that AXA had continued to use the mark in a fashion consistent with maintaining the trademark after dropping it from its name, noting that the company had failed to enforce the mark or renew it in the interim. It would seem to be the opinion of the court that the use was token use for the purpose of trying to hold onto the legal rights, rather than genuine commercial use that is in the spirit of trademark law. Thus AXA finds itself facing an uphill battle in trying to regain a mark it held for over a century.
While most businesses likely don't have a history spanning centuries to uphold, there are valuable markers of your identity and brand that every company should covetously guard and maintain. Rebranding can look like a good idea from the perspective that doing something is better than doing nothing, and while it can be good to get an update on your brand if it's become old and stodgy, it's also worth considering the equity built up over time. A big change that doesn't work out might not have a way back if you stand the risk of losing your marks to competitors, and then it's years of work on branding down the drain.