But from what you have said if your worried about it or feel YOUR properties are going to devalue a ton why not sell out now.. take all the great appreciation you have gotten..

The cash income will be too small relative to your investment and you will be ask risk of a downturn devaluing your total investment. 

They must be steeply devalued and it is best if there are none or very few at purchase and that you can quickly sell off to home buyers.

Also, once you discount the property 3% you've basically devalued the property by that much, in comps, etc., so will have to make it back up. 

-Will this devaluation mitigate all of the returns gained during it's time as a rental?

They generally devalue the property by 3-5% here because people care much more about the aesthetics of their home than saving $10 a month off their electric bill.

This may not directly relate to your question, but I would like to add when purchasing property, consider negotiating on a lower purchasing price by using CAPEX as a reason for devaluation on property, especially if it's an older building that may need more immediate repairs.

This will avoid the risk of losing a tenant over a rent increase and regardless of how good your tenant is it is poor business practice to supplement a tenants rent.It is not good business to not raise the rent as not only are you supplementing a tenants rent you are also devaluing the resale of your property.Research your local rental market adds and put your rent at market for the size and location of your property.

Adding over a roof with a good dimensional shingle will not devalue the property one bit. it may reduce the life of it from 25 years to 20 but thats it. if its in really bad condition you may have to tear off the old roof but if its not it could save you about $1,000 in tear off costs.

If you are accepting dividends in exchange for asset devaluation, you better have a good healthy bank account.