Where it will most likely have an impact is in the real estate markets in the specific types they're targeting - developers are gonna LOVE this.  

All real estate is local so the impact of online retail is going to vary widely.

If you put in effort, you can create some impactful/win-win interactions and long-term investor relationships.

I have been thinking about STR's and buying more rentals in general but now with that kind of giant buying up condos/SFH/multi's what impact do you think this will have on the rental industry in general (and housing for that matter) and STR- hard for most investors/buyers to compete with something like a hotel chain behemoth when it comes to purchasing power and could drive prices crazy in desirable areas, not to mention the points and perks they can offer for staying on their properties?

There are ways to decrease tax impact if done correctly. 

If you are able to make your normal car payments on a monthly basis, I wouldn't be too concerned about paying it down unless it impacts your DTI to the point that you cannot get financing for investment properties. 

Paying off any types of loans won't impact the gain or tax you owe. 

You are absolutely correct, forcing new investors to mitigate any and all environmental issue in an asset is one possible solution, especially if the bottom line makes a profit.

And secondly, is there anyone here who had cashflow properties in the 2008-2009 recession that were greatly negatively impacted (like, was it harder to find renters or did you have to lower your rents, etc.?)

Account Closed, I don't think this is a good plan at all.Besides losing 20% of your income, there are a number of other disadvantages:You can't force appreciation with a 4-unit.You're at the mercy of the fickle and emotional residential market.Based on that market the property may be worth significantly less than as a 5-unit commercial, instantly losing you money and impacting your ability to get a new loan.