I have inferred from this article that the west Pacific warm pool is probably why this el nino isn't going to remain east-based, which is congruent with what others have been saying about the forcing getting pulled west..
"In the present work, consideration of the onset and evolution of El Niño events (Figs. 1 and 2) has led to the innovative classification of El Niño diversity, and uncovered an El Niño onset regime change from an EP origin to a western Pacific origin in the late 1970s (Fig. 3). The onset changes and more frequent occurrence of the extreme events in the past 4 decades arise from a background warming in the equatorial WP and the associated enhanced zonal SST gradients in the equatorial CP"
"the change of El Niño in the late 1970s coincides with a rapid warming in the Indo-Pacific warm pool, suggesting that the recent rapid global warming may have had an impact on the observed El Niño changes."