I would have viewed it the same way I viewed the move to 4E, "I can still go by the 3.5 E rules". Then Paizo did Pathfinder 1E (aka, 3.75) and I didn't look back until 5E under the OGL 1.0a. Biggest difference? I would have looked at Pathfinder 2E straight away this time. Now, I don't trust them...