A few changes are coming to plugin developers with REAL Studio 2010r3. We make progress on this and also REAL Software fixed a few of the bugs we found in the latest final candidates. So we are confident, we can have our 10.4 plugins working well with the new REAL Studio release.
Of course our version supported table will soon be updated to show plugin version 10.4 as minimum for REAL Studio 2010r3. This does not mean that older plugins will stop working if you upgrade REAL Studio, but we recommend keeping the plugins up to date.