I stay far away from services like 23andMe because of their user-hostile terms (at least that's the impression I got when I last scrutinized them a few years ago).
To me the ideal DNA test would be one I process myself at home, without sending anything to the cloud. I recognize that's not viable since most of us lack home laboratories.
Next best option would be one where the sample is submitted anonymously and results accessible under a system-generated ID code. That would alleviate some of the risk if you or your partners screw up in terms of privacy and security (it's naive to ignore that possibility - look at how many Fortune 500's have been breached or suffered human error).
A user could "opt in" to share identifying information (ideally only to the extent they're comfortable - e.g. I might be willing to submit coarse data like racial background, age, etc. while withholding my name and address).
In all cases I would still expect to see very strong, binding language in both your agreements with me, and those with the labs you subcontract out to, assuring that my data will be kept confidential and all traces deleted (including from all backups!) when I request.
Regarding re-sequencing and long-term storage for privacy concerned users: give me the option to download the raw data (compressed and encrypted?) and delete it from your platform. I can re-submit to you in a few years for an updated analysis. That avoids the cost of re-sequencing while, for privacy-conscious users like me, minimizes the window in which you storing my data could cause me harm.