Your 100k loan just isn't that much after adjusted for real inflation should this occur.

Have they adjusted the sales price during the past two years?

They can't be evicted if they are renters, and most homeowners aren't underwater with adjusting mortgage rates or balloons coming due in waves so they aren't going anywhere either. 

Once you start adjusting your process to suit every seller, you end up losing money on terms you didn't want.

Ultimately - your accountant is best suited to answering this question.Your gain is sales price less adjusted basis where adjusted basis is purchase price + improvements - depreciation.You may have a gain on the sale, you may have a loss on the sale - only your accountant knows.If you have a gain(depends on how much) and you plan to continue being in real estate, you may want to consider doing a 1031 exchange.

I mean, i'm involuntarily become a landlord but it is what it is, need to adjust and work with the current situation.  

I learned to adjust the price based on the interest (or lack thereof) aka number of inquiries I received.

This is a little harder to do with a HELOC as that rate can adjust on you over time. 

Being flexible helps you adjust to uncertain times and circumstances in a manner that gives you better results.

As far as the tenants go I do plan to make some adjustments as far as length of lease and raising the rent as they are both on a yearly and only paying 575/m.