As is the case with Solitude and Subtlety, this card is going to drop in price at the release and then slowly build up the price as the time goes.
Grief will be played in most eternal formats, but it looks like commander crowd is not particularly big on this one. This could be an indication of an even steeper drop as soon as the card hits the secondary market.
But it could perform exceptionally well in modern and legacy, and if that's the case, then the price will correct itself. The question remains: how strong this correction will be?