It kind of makes sense if you look at the distribution and production of top draft picks over the last decade or so.
The East already had the Big 3 in Crosby, Ovechkin, and Malkin; and these generational (or near-generational) talents have won 3 of the last 3.
But looking beyond that, over the past decade, the Eastern conference has also been adding top picks at a higher rate. If I'm counting right, of players selected first or second overall, 13 have gone to the East since 2008, and only 7 have gone to the West. Dahlin and Svechnikov going as projected would bump the East up to 15. Obviously there's more to drafting and team-building than top-2 picks, but if we consider that they have the highest likelihood of becoming impact players, we're looking at something like:
East: Stamkos, Hedman, Tavares, Seguin*, Barkov, Eichel, Matthews, Hischier, Dahlin, Svechnikov
West: Doughty, Hall*, RNH, Yakupov, MacKinnon, Landeskog, McDavid, Laine
The verdict is still out on Hischier, Dahlin, Svechnikov, but just looking at the groupings above, and with Hall now being in NJ, I wouldn't be surprised to see the balance of power remain in the East for the foreseeable future.