Can I still change course toward succession after I've started planning a sale to an outsider?

Generally yes, especially if you haven't signed a binding agreement yet. Early conversations, marketing the business, or even a signed letter of intent with an outside buyer are typically non-binding on the core decision to sell, which means changing course toward a family member or key employee instead is usually still available to you legally.

The nuance is what you may have already committed to along the way. A letter of intent often contains provisions — confidentiality about information the buyer has seen, or an exclusivity period promising you won't negotiate with anyone else for a defined window — that remain binding even though the price and structure aren't. Walking away to pursue succession instead could put you in breach of those specific terms, even if it doesn't breach any obligation to actually sell to that buyer.

It's also worth being honest with yourself about why the switch is happening. Changing course because a genuinely better succession option emerged is different from changing course to avoid a difficult negotiation with the outside buyer — the second can sometimes be solved within the existing deal rather than by abandoning it. A business lawyer can review exactly what you've signed and what changing direction would actually involve.