Where you are will determine if its really useful to have 70cm for chasing. In Georgia, it was almost a necessity, as at least a dozen counties, particularly around the Atlanta and Savannah Metro areas, use 70cm, as do several of Peach Tree City's primary 'backbone' repeaters.
In areas of denser population or the really highly organized programs like NWS PTC, you'll likely find some nets that operate on 70cm, at least as a backup. Seeing as the 2 meter repeater frequency pairs have been depleted in huge portions of the country, 70cm is seeing the most rapid growth in repeater coverage right now. It's logical to assume that SKYWARN will start to see more and more activity on that band as time goes on.