Glaswegians queue up for the iPhone 5. Photo: Stevie Doyle via The Mac Observer

FORTUNE — Noting that Apple AAPL  can’t build iPhone 5s fast enough to meet demand, a slightly defensive Gene Munster on Friday rattled off the reasons Piper Jaffray still believes Apple will sell at least 49 million units in the quarter that starts next week:

  • 65% of consumers surveyed last summer said they planned to buy an iPhone for their next phone.
  • In the same survey, 94% of iPhone owners said they planned to buy another iPhone.
  • In a more recent poll of 1,000 consumers online, 35% hoped to get a smartphone for Christmas. Of those consumers, 63% hoped to get an iPhone.
  • Despite negative reviews for the new Maps app, 71% of tweets about the iPhone 5 after the announcement were positive compared with 49% for the iPhone 4S.
  • Demand remains high. In a survey of 20 stores, only 4 had iPhone 5s in stock, and they were all Sprint phones for sale in smaller U.S. cities.
  • Given how many consumers say they want an iPhone, it seems unlikely to Munster that they will opt for a different smartphone instead of waiting for an iPhone 5.

Summarizing his three reasons for optimism, Munster writes:

“We continue to believe that by December, supply and demand for the phone should be close to equilibrium. Second, if supply issues do constrain December, we do not believe consumers will ‘give up’ on the iPhone in favor of another phone. Third, consumer sentiment on the iPhone remains high despite reported issues with Apple Maps, which we believe suggests that the Maps product is not causing a user backlash.”