I doubt if slabbing of strikes will catch on in the forseeable future for the following reasons.
1. Collector's will not pay $10 to $30 per strike to have them graded and slabbed.
2. Most strikes are mint (in the capsule) and vary little in grade with exception of a strike that is impaired,mishandled or circulated.
3. Few collectors could tell the difference from a mintstate 69 to mintstate 70 graded strike.