You are probably not very old but anyway . Let's say you die in accident. Nobody will be able to use your code until either copyright is repealed (the boomers half life has kicked in long enough such that they are irrelevant and we can change copyright) or you are 70 years dead.
I understand you wanting to keep your options as long as possible. I see three options for you:
- leave it without license and hope you will be able to license it as you want. Take no contributions. Have total freedom. Never accept contributors.
- pick any non public domain equivalent license and require all contributions to allow you to relicense their contributions in the future. When you change the license in the future the all previous version released under that license stay that way.
- pick a public domain equivalent license 0BSD preferably. All contributions under that license means you and their code and be relicensed by anybody including you. If you later decide to relicense you can do so without needing the contributors ok. Old versions stay in the public domain. Newer code (after relicensing doesn't).