I don't know if it's the position of the IRS in general because I didn't ask. However, the agent did not hesitate in explaining to me what to do. Maybe the IRS handles changes through Ogden as well, but it seems as though they try to discourage procedures that require human involvement.
Looking at Form 5500 again, Line 4 does report changes in EIN as well as plan sponsor and plan name. As I think about it more, I think our issue perhaps was that the new sponsor had a prexisting plan with the same plan number that we had to fix by filing an amended and new returns because Line 4 does not change plan numbers (?). The IRS definitely issued a penalty notice for failing to file a Form 5500 after the EIN/sponsor changed, and the issue was resolved per the IRS agent's instructions.
Even if one follows the steps I outlined, there is no indication that the "old" plan was terminated. The reporting would be similar to a plan merger with the assets and participants being treated as having been transferred to the "new" plan, and 1099-Rs are not issued for plan mergers. The old plan files a final return and goes away.