If you choose to renew, your subscription will be fully supported for the term of your subscription, since that is before the end of 2010 when support stops.
OneCare will not automatically "update" to Morro as it is a different product. You will likely receive communication on steps to take to remove OneCare and install Morro when it becomes available. Note also, that it won't likely be released in June - the press release said 2nd half of 2009 and it has not yet been offered for testing.
-steve
Microsoft MVP Windows Live / Windows Live OneCare & Live Mesh Forum Moderator