If I convert my CS6 license to CC, am I going to be stuck with a susbcription?

CC is not available outside of the subscription. If you decide taking CC you will need to take a subscription. There is no "upgrade" path available. CC will be a new license. You don't convert your CS6 license to CC, you will keep eternally your CS6 license, but there are still consequences, if you install CC:

• If you install CC on the same computer than your CS6 installation, the subscription will also take over CS6. That's not problematic as long as you are subscribed, but if you decide to stop the subscription. You will need then to uninstall completly and reinstall.
• Edited data will not be downwards compatible, so after a while you will need anyhow to continue the subscription or you will need to recreate a bunch of your work, if you downgrade to CS6. 

There are also consequences to stay with CS6:

• A system update may make your CS6 stop working.
• You may experience unexplained errors because of your aging system or software.
• You can't cooperate with other designers, because you use outdated software.
• Programs evolve and some functions add to your productivity. Also standards are changing especially for the web, and your products may not be adapted to the new standards.
• There are no bug fixes and the software may be vulnerable.
• You may not be able to migrate your old software to a new computer because of system incompatibilities.

You can't convert CS6 to anything.   It's discontinued.  

Creative Cloud is enitrely separate.  When you stop paying for it, your access to CC software & services stops working.  But CC has no direct impact on your old software. 

CS6 allows installing & activating on 2 computers (only use 1 at a time) so why can't you do what you want now?

Cloud Plans https://creative.adobe.com/plans are ONLY by subscription, not by one time payment

SOME programs are available Monthly https://community.adobe.com/t5/Get-Started/Being-charged-for-a-full-year-when-i-m-on-month-to-month/td-p/10248222 - links and pictures
-the special Photography Plan is ONLY available on an annual plan, with monthly or 1 annual payment
https://helpx.adobe.com/creative-cloud/help/manage-cc-individual-membership.html

If you install any part of the Cloud, even a trial, your CS6 will stop working when you stop using the cloud program(s)

As soon as you install any part of the Cloud, even a trial, it replaces your program management system
-if you plan to keep using a serial number program you should NOT install a Cloud program, not even a trial
-Read Cloud takes over https://community.adobe.com/t5/Get-Started/Get-off-the-cloud/td-p/8075485 for some ideas