In ten years of running enterprise programs, I have never worked at a company that did not reorg. Most of them reorged during active programs. The programs that came through intact shared a few traits that the ones that didn't lacked.
The first is written scope. A program with its scope in someone's head survives as long as that person's role survives. A program with its scope in a document survives the reorg because the new leadership can read what it is. Write everything down before you think you need to.
The second is stakeholder clarity. Reorgs change who owns what. The programs that stall are the ones where the TPM has to spend three weeks figuring out who the new sponsor is and whether the new sponsor cares. Map your stakeholders and their successors while the org is stable. It sounds paranoid. It is practical.
The third is a clean milestone record. When new leadership inherits a program, they are making a fast decision about whether to continue, modify, or kill it. A clear record of what was decided and why, what was accomplished and what remains, makes that decision faster and usually more favorable. A program that looks confusing from the outside gets canceled.
Reorgs also create opportunities. When structures change, priorities get re-examined. A program that was underfunded under the old structure sometimes gets the resources it needed under the new one. That only happens if the TPM is ready to make the case quickly. Know your ask before the reorg happens.