i personally see the "shortage" of lenses as being a bit ridiculous of an argument for anyone other than professionals.
Really, how many lenses do people own? Sony have a comparable lens at every market point except the ridiculous, which Joe Average would never consider. Primes, zooms, tele's the basics are covered, and if you punt for G glass, its as good as the high end Canon/Nikon glass.
For used the market is increasing every day, and if you are on a tight used budget then there are the whole history of Konica-Minolta AF A-mount lenses to choose from as well. The only things average Joe loses is the ability to hire, thats it (in terms of lenses).
fwiw i bought Sony, and have since bought 3 lenses and sold my kit lens. I wouldnt have any more (or different) lenses had i bought Canon or Nikon, as those three cost me £1300.
Get Sony if you want Sony, understand the limitations and benefits of the new mirror system and see if it fits for you. The technology is here to
stayand is being incorporated into their higher-end bodies. Nikon/Canon may be known for their photographic experience, but Sony are known for their electronic and so quite capable of leading the market in that area...
I would only switch to Nikon for their ISO levels, and i felt the Canon felt no better than my Sony for build - the equivalent Nikon was slightly better. The lost light is a bit of a peeve, but its not a deal breaker - the 1/3rd loss is easily recoverable in post.