They prefer the middle/southern part of the country because the laws are friendly and prices are more affordable.

Some funds offer preferred equity and common equity in the capital stack.

Preferably stay for one year and find another house.

Time with family, giving to a preferred charity, or just having nobody buying your time. 

Businesses are the opposite: their primary purpose is cash flow and while you can create a sellable asset, anyone who has ever tried to sell a biz knows it's a lot harder to sell than real estate. 

I have a C-Corp (no assets) as the Prop Manager  to manage leasing and rental collection for all 4 LTRs.

I understand the seller wants to move froward, but if they are not willing to give you information on the asset that you're purchasing, that is certainly not a good sign. 

It seems like each option could work depending on your long-term goals for those assets.

It means that you, as the purchaser, cannot close on the purchase of the property until (subject to the terms of the contract) the seller identifies a new asset to acquire with the proceeds of the sale. 

Without rent control i either raise their rent far above market rents so they give me notice (my preferred method) or i simply do not renew their lease.