Sounds to me like they're just reverting back to pre-failure engine parameters. Not that they've come to an AhHa moment where this is a fix...
From the supplied link by the OP
"Hamilton will revert to the engine he used in Singapore for the Japanese GP this weekend, while Rosberg will continue with the power unit he ran in Malaysia. As a precaution, Mercedes is introducing revised running parameters for the works team, as well as customers Williams, Force India and Manor.
Those parameters will include, but are not limited to, a different and more conservative oil specification...
However, those changes have been delayed until Mercedes has conducted further analysis from stripping Hamilton's failed unit."
We're getting way ahead of ourselves.