What are the possibilities of me losing my TS or Secret clearance if I were to be administratively separated?

Too many urban myths out there. If in the IRR, you don't have a billet, hence the clearance is withdrawn. If you get out, the clearance is withdrawn. If you hold a GS, contractor, etc. type civilian position that requires a clearance, the security manager for your civilian work then uses the basis for your clearance to reactivate under their sponsorship to the same or lower level. If the basis expires, you do the typical renewal drill by filling out the application under the current sponsor. If your civilian work doesn't require you to have a clearance, then you'll have no clearance. You don't own a clearance. The sponsor does. No sponsor, no clearance.

As mentioned, you will absolutely NOT have a clearance once you get out. What you MAY have is ELIGIBILITY for a clearance.
Each Clearance investigation grants eligibility for a certain time period (TS - 5 years, S - 10 years, C - 15 years). The position you hold will grant the actual clearance, based on that eligibility. Once you get out, you no longer have a clearance requiring position, therefore you no longer have a clearance. You maintain your ELIGIBILITY for a clearance until the investigation "expires" for lack of a better word, or until specific derogatory information (DEROG) is entered into your record. If you apply to a new job requiring clearance, and your most recent investigation is still current, AND you have no DEROGs, then the gaining "unit" (contractor, GS, whatever), can re-instate your clearance with just paperwork and no investigation. If your investigation is "expired" then a new investigation must occur. If you have a DEROG, then the basis of the DEROG must be investigated and separately cleared, regardless of whether your investigation is current.

So.... no clearance, definitely. Maintain eligibility, probably. It depends on the basis of the administrative separation. If it is something like medical (non-psychiatric) or failed fitness test, no worries. If it is administrative in lieu of court martial or psychiatric or something that would raise a red flag, then the Navy has a responsibility to do a DEROG prior to your separation and put it in your OPM record.

This is a VERY "dumbed down" non-technical version of things. There are always specific instances that don't follow the overview, and I kept it general on purpose. This isn't EXACTLY how it works - but it is the easiest way to explain it in a (relatively) short post.

Your clearance is tied to the position you hold, not who you work(ed) for. If your employer requires you to have a clearance for the work they need you to perform, then they are responsible for granting said clearance and "need to know" requirements. You won't keep a clearance just because you had one one in the past.