I'm sure NRZ will have some mark to market write down on MSRs but these are NON-CASH adjustments that have zero affect on cash flow, and arguably don't even reliably indicate changes in future earnings. What really is amazing is how many investors overreact to such accounting changes...both on the up and down sides. Not long ago they had a large write up and many people are still counting that book adjustment as undistributed earnings available for distribution.
Interest rates and most existing mortgages are already very low, to the point that only 5% or so could reasonably be refinanced with a small benefit to the owners...even if the short rate goes back to zero.
In the long term very low rates stimulates the economy, improves everyone's job and income prospects, and encourages many to buy a home and have a mortgage that they would not be willing to take on if rates were higher or the economy was worse.