Umm.... that's not new and that's not how it works.
They can't get a rank bonus beyond +3 unless they have a rule that says otherwise, and that rule is dependent on rank bonuses not just ranks, ranks is a descriptive informal like "columns", it is not a keyword like "trample" in magic. "Rank bonuses" lets them add up to +3 to their leadership, so yeah, they go up to 8 when they are piled deep, but shooting them lots can quickly make it drop, and flanking them means they get nothing to their LD. Further, in the old book they could take their general's LD and add the ranks on top of it, which let them get up to 9 or ten from a lord general, but only on ranked units, and skaven tend to have a lot of skirmishers....
I personally think that skaven aren't gonna be that menacing against lizardmen, since we are less likely to panic from their pew pew crap. We also don't have to worry about their dumb monsters and harassment on the flanks, because normal boring skinks can handle both problems. Seriously, just a unit of 20 skinks in non-skirmish formation will ruin a rat-giants day, and soak str 6 ap bullets better then Warriors of chaos, and for 5 points instead of 16.
