I don't know if twitter is expected to grow to the same user size as Facebook. Perhaps that's the problem, the analysts and investors expect a Facebook clone.
If twitter is profitable, surely that's good enough.
Profitability doesn’t appear to be in Twitter’s (TWTR) future anytime soon. Losses are increasing, membership growth has slowed, and the company’s stock price is down 28 percent since the start of the year, amid a broader selloff in the Nasdaq (NDAQ). But there’s some good news: Twitter’s ad revenue is projected to reach $1.1 billion in 2014, an increase of 84 percent from the year before, according to researcher EMarketer. That’s due in no small part to Twitter Amplify, a year-old program that has allowed the company to snag a piece of the billions of dollars spent annually on TV ads.Twitter Ads Revenue Predicted To Reach $1.1 Billion In 2014 [businessweek.com]