To best answer your question, the key would be do you want to save any of these backups?
You basically have two options:
- Inherit the current backup set with the new Mac. (Not really recommended.)
- Archive, these backups to another drive. Then fully erase the backup drive. Finally start a new Time Machine backup set for your new Mac on this drive.
Also, as Jack-19 has mentioned, if you want to migrate any data from your old computer to you new, DO NOT erase the old computer's backups yet. Using either the Setup Assistant or Migration Assistant on the new Mac, you can migrate this data from this backup set. Once done to your satisfaction, you can then elect to Archive, Erase, and then, start a new backup set for the new machine.