What is Twitter, exactly? That's a question the company has been struggling with ever since it went public two-plus years ago, just as user growth started to taper off. 

The simple answer -- a social network consisting of status updates no longer than 140 characters, displayed in real time -- was deemed insufficient by Dick Costolo, Twitter's then-CEO, who thought the answer might be ordering tweets by relevance, not chronology. 

Now Costolo's successor, co-founder Jack Dorsey, is tinkering with the other half of the original formula. According to Recode, Twitter is developing a new feature that will enable users to post tweets of up to 10,000 characters. It's expected to launch by the end of March. 

Twitter's user base may not be growing as fast as the company would like, but it does have a loyal core -- loyal to the product as it was first envisioned, that is. Just about every time the company has changed the way it works in some substantial way -- introducing advertising, adding photos and videos to tweets, "threading" conversations -- some segment of that loyal core has taken to the ramparts in protest. (Interestingly, a rare exception was the most direct precursor to today's news: the raising of the limit on direct messages to 10,000-characters last August.)

Predictably, the idea of 10,000-character tweets has its detractors. "Did twitter just die?"  tweeted Modest founder Harper Reed, whose social media wizardry helped get Barack Obama reelected. "Is there something in 4q usage trends that shocked them silly?"  wondered tech analyst Tero Kuittinen of Magid Associates. 

Others have pointed out that the expected format of extended tweets -- a digital card preceded by a short click-to-expand teaser -- makes them a natural alternative to Facebook's Instant Articles. The larger social network created that product in a bid to entice news publishers to upload their content directly to its servers, where users can access it faster. 

Meanwhile, The Information's Amir Efrati raises an intriguing question: Insofar as the ability to publish longer-form content will put Twitter more directly into competition with Medium, will Medium's founder, Ev Williams, be compelled to step down from Twitter's board of directors?

A Twitter spokesman did not immediately respond to an email requesting comment on Recode's report.