One important point to acknowledge here is that, should Russia decide to return to a monarchy, there is a succession dispute as to who the current monarch would be between Maria Vladimirovna and Andrew Romanov, who interestingly enough, actually lives in Marin County, California. He was also born just three weeks after the founding of the USSR.
Maria Vladimirovna is officially endorsed by the Patriarch of Moscow, so it's hard to imagine anyone else being chosen if they did restore the Romanovs.
Where did you read this? I can't remember any speech from Patriarch Kirill, where he supported reconstruction of monarchy. Also he isn't independent powerful figure.
I don't read Russian, but I trust Wikipedia's interpretation of
this article (backed up by Google Translate, ha), where he doesn't endorse her for the throne (and specifically disendorses the monarchy generally) but does say she is the rightful successor to the House of Romanov. Presumably, in the unlikely hypothetical where the monarchy were to be restored, it would be with his support.
A monarchy of course wouldn't necessarily be Romanov. The House of Putin, anyone?