Google Apps aims at improving security by offering users same login process across all its services. To an extent, this is true. However, the decision is likely to rattle feathers with companies that will not rejoice having branding removed from their pages. It will also take some time before people get accustomed to the change.
The redesigned page will make it easier for you to switch between accounts. Google has started consolidating accounts as we have seen so far. You will have an opportunity to login in a specific account with the same password. Logging in and out will become much easier and easily manageable. You will have no difficulties adding and managing accounts on Google apps. This comes in the background of a recently unveiled chrome app launcher that stores all your Google apps on chrome.
Google intends to release more information on the proposed updates to system administrators so that the same can be passed to end users. It has however not yet put a specific date for the changeover. Keep posted to know when Google releases the changeover date.