V2 API support ending with Oauth changes?

I got a notice that all applications must be copied and update to the new Oauth endpoints...ok, but they reference the V3 API Oauth endpoints as being the ones that need to be changed.

My app still uses the old V2 API and the Oauth endpoints that went with it:

https://oauth2.constantcontact.com/oauth2/oauth/siteowner/authorize and

https://oauth2.constantcontact.com/oauth2/oauth/token

Will these continue to work after the August 23rd shutdown of the 'previous' service?

I just want to make sure I don't have to cram a V3 API update into my customer's summer holiday schedules...