The Silver Lining of Decreased Values
Declining property values aren't all bad news. Documented drops in value can help you reduce expenses for property insurance and taxes.
Property insurance premiums are based largely on a property value. If current premiums reflect outdated, inflated valuations, your properties may be insured for more than they're worth. If you need to file a claim, it likely that the insurer will determine its payout using the more recent, reduced value, so there no point in paying the higher premium.
Similarly, you may be able to reduce property taxes by arguing that they're based on inflated assessed values. Few taxing authorities conduct formal appraisals of properties annually, so it possible your taxes are based on the higher market values of a few years ago.