Every year, rents increases, outstanding mortgage balance decreases, you may refinance into more ideal lending terms also.

Depending on how many restrictions and what restrictions you put in the new deed (if any) it may decrease the value of the new lot BUT... it may not especially if those restrictions are congruent with the types of properties in the area AND doing so will then ensure that whoever puchases the lot next door to your existing investment property won't be able to build something that will decrease your property value, in fact if you do it properly the restrictions should help INCREASE your property value on the lot you retain. -- So really, yes any value you loose on the split, you should make up for in ensuring that the property next door (whenever it is built) is not run-down and of a certain caliber. 

The first tax benefit of real estate is that the cash-flow and appreciation grow tax free(in general).Cash flow will likely be offset by depreciation and appreciation is not taxed.If you are making 8% on real estate(combined cash flow and appreciation), you money will double  in 9 years.If you make 12% on real estate, your money will double in 6 years.There are other strategies in real estate(time involved in real estate) where you can create 'paper-losses' to decrease your W-2 wages, interest, dividends.I normally don't like this route too much as I think people can focus their time and attention more on other tasks that can generate a higher hourly return.Best of luck.

What other scenarios could I possibly run into besides property value decreasing that could cause issues?

You could still get the tax deductions...rents will likely go up, interest rates will likely stay flat or decrease slightly, Austin has a great outlook long-term. 

We haven't noticed any decrease in bookings.

For instance, Sacramento CA has seen very little change, whereas Phoenix and Tucson AZ have seen a much larger decrease in revenue. 

Is the population growing or decreasing in that market?

It looks like you have a business loss which you can use to offset other forms of income.I don't think you sold it less than its worth, you likely tried to get as much as you can.Squatters decrease the value of a home, especially if you are selling the house with them in it.

If anyone has apartment sector specifics on potential loan rate resets, please post the details.From Avison Young, about the 2023Q4 Raleigh-Durham office market report, "Class A availability has reached a post covid high (27.3%) as demand for office space slows and occupiers decrease overall hiring."