Why you even published this "news"?
1. You did not explained the reason to this decision. If you say the SQL does not performance well for Exchange, is this agreed with SQL team? How bad performance problems you found out? Where was the real information on this?
2. "High Availability benefits", do you mean by that the SQL have not HA benefits? Really?
3. "provided customers with further opportunities to lower their storage costs", I want cheaper solutions for the archiving. And for the cheaper storage solutions, try this:
a) Today I do have so many DBs that SIS doesn't give any benefits
--> I need more storage
b) Today I have started to use CCR
--> I need more storage
c) Users needs larger mailboxes, for backup/restore SLAs I need more
DBs
--> I need more storage
d) E2010 and database groups...
--> I need more storage
4. I assume that one of the biggest reason (on the MS side and customers side) to not replace the ESE by SQL is worry about the personal work. If someone else do the database planning, maintenance and other works, we do have less work to do...
5. Those who are saying that SQL and Exchange together are more complex than today, could you give some arguments for this? If your company does not have SQL knowledge, but Exchange, then I agree. But in all other cases I don't see any reasons yet.