You'd have to think MySql's demise is highly likely which would likely be a good thing for PostgeSQL, more demand for non-oracle licenses and lower costs in todays economy means people will look for ways to reduce price with a good database and PostgreSQL will be a respected solution.
I would tend to disagree that it will die. The recent new release of innodb (http://www.innodb.com/wp/2009/03/11/innodb-plugin-version-103-for-mysql-5130-32-33-released/) suggests that Oracle is not really interested in letting mysql die completely. If I had to guess, I would say that mysql would probably be somewhat revitalized by the acquisition. Sun has typically tended to be where good ideas go to suffer a lengthy death... Oracle moves deceptively yet true to its convictions, and never without a keen eye for the market.
My guess? Oracle drops a few dollars on innodb, maybe even a few back into Mysql, and pushes it to new heights in the open source RDBMS world. I see some tough competition for postgres coming up, but hey, competition has been known to drive innovation before. I would say competitive times lay ahead.
