The phrase "are now outdated" is correct and usable in written English.
You can use it to describe something that is no longer current or relevant, often in the context of technology, trends, or information.
Example: "Many of the methods we used in the past are now outdated and need to be replaced with more modern approaches."
Alternatives: "have become obsolete" or "are no longer relevant."
"Laws on prostitution are now outdated, misinformed and redundant.
A target of having 15m people on ARVs by 2015 was based on clinical guidelines which are now outdated.
On a more hopeful note, due to the declining price of renewable energy and energy storage, many of the economic assumptions that informed the NDCs when they were drafted in 2015 are now outdated.
While the finishing schools of the 19th and 20th centuries are now outdated in the west, an industry of manners worth more than 6bn rupees (£70m) has mushroomed in the east in the last five years, as young, urban Indians prepare to embark on global careers.
According to Professor Diamond, who is now learning his 12th language, such assumptions are now outdated, with more recent work suggesting no great differences in the cognitive and linguistic progress of multilingual vs monolingual children.
Furthermore, they were based on small study samples, not generalizable to the Swiss population, or are now outdated.
Medical knowledge has advanced significantly since then, and the F.D.A.-approved regimen is now outdated.
"The world's agriculture and food system is now outdated and inefficient," Mr. Gates said in the speech.
The cold-war logic that led to creation of massive stockpiles on both sides is now outdated.
Don't feel you have to list all your abilities on your CV, especially if, for example, a particular technology is now outdated.
(Another quiet song was one of the show's few missteps; as righteously as Pink performed it, "Dear Mr. President," her outraged letter to George W. Bush, is now outdated).
