There's no "failed strategy" involved in this chain of events. The only time RBG could have retired on her terms was before the 2014 midterms, after Reid nuked the filibuster. Not knowing what was to come either politically or health-wise, there was no great reason for her to consider retiring then. By 2015 there was no way a RBG clone gets confirmed. Waiting for Clinton's anticipated election wasn't a strategy, it was just the only remaining hope.