According to your theory if there is no successor then we can all teach what we want and we would all be right.
All who are "born again" of His Spirit, the Holy Spirit, are to hear the "mind of Christ" that is deposited within them, as they study His words (John 3:3-8).
KJV- John 16[
13] Howbeit when he, the Spirit of truth, is come,
he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come.
RCC-DR Bible-John 16:13 But when he, the Spirit of truth, is come,
he will teach you all truth. For he shall not speak of himself; but what things soever he shall hear, he shall speak; and the things that are to come, he will show you.
> Because Jesus is "the truth", the Holy Spirit will only teach/guide us into His Truth.
Therefore, concerning every biblical topic, among men "there can always be more than one lie, but by His Spirit, there can never be more than one truth"- Earburner.