The new Legend and Lore is up and Mearls discusses taking a modular approach to spellcasting. It sounds like rather than assigning a spellcasting system to classes, the goal is to allow DMs to determine which magic systems are used when building their campaign settings. The DM will be able to choose between spell points, vancian, and other systems like casting as a 3e sorcerer.

If correct, this is, in my opinion, the best news to date about the playtest. I like spontaneous casting from 3e (including the spontaneous divine casting variant from Unearthed Arcana).

This option, however, won't be in the next playtest package, but one of the packages following.