Will spousal support be reduced when I retire?

Most likely. 

A supporting spouse's attainment of retirement age may constitute a material change of circumstances for purposes of a motion to modify a spousal support order.  This depends on the nature of employment, whether the supporting spousal will receive a pension, and what terms are included in the Marital Settlement Agreement. 

A material change in circumstances has been found when the supported spousal became old enough to access a retirement fund without penalty and where the accessibility and possible increase in value of the obligee's share of the retirement accounts were part of the parties' expressed reasonable expectations in entering the stipulated judgment. In re Marriage of Dietz, 176 Cal. App. 4th 387, 97 Cal. Rptr. 3d 616 (4th Dist. 2009), as modified, (Sept. 2, 2009)

If you are interested in learning more, you can contact me at Amanda@gordonfamilylaw.com for more information.