It is entirely possible that your original launch vendor may become unavailable. Even with the CubeSat standard format, this can leave you without a rocket and facing a possible interface/integration quandary if your new launch provider uses different specifications or has different driving requirements. If you go with an alternative sole-supplier form factor such as TubeSat (typically to save on cost and overhead), your risk if you shift launch providers can increase as well.

I am launching my Project Calliope picosatellite on an InterOrbital Systems (IOS) rocket. IOS invented the TubeSat format. What if InterOrbital fails—its rockets all blow up, it runs out of money, it decides to do interpretive dance instead of rockets? Is Calliope dead?