Mmmh, I don't know... I mean, 2x2 grid app covers and 3x3 app covers are not compatible size-wise to be placed on the same "row". For that to work, you should have a "big" cover size (same as the present one) and a "small" cover size with an area of 1/4 of the big one (and I think that would be too small to be readable). With the size Sailfish covers now have (I think the small ones have 2/3 of the width/height of the big ones), you cannot have a big cover, let's say, on the left, and a bunch of small covers to its right like in WP8.
In different rows that is possible, I think. I don't think I would use it, though