I don't think that you can consider the Office 365 exam as a "replacement" for Sharepoint 2010, since the content of both exams is *very* different. It is true that the Office 365 exam contains a small section that deals with "Managing Sites with Sharepoint
Online", but its coverage is minimal when compared with the depth of coverage of Sharepoint in exam 77-886. If you need to prove your skills on Sharepoint, I believe that you should go for the Sharepoint exam rather than Office 365.
If you want a replacement for the exam on version 2010 of Sharepoint, then consider taking the exams on Sharepoint 2013 (70-331 and 70-332).
http://www.microsoft.com/learning/en/us/mcse-sharepoint-certification.aspx