the collective penalty, or the end of defensive game in the knock out stage
It has been very common to see World Cup matches in which a team tries to draw by any means in the expectation of winning in the penalty shootouts. There are several examples. In the last World Cup, the nasty Ukranian game against Switzerland was one of those.
With the Collective Penalty, the team ending the match with more talented players will probably win. The result of a Collective Penalty with 5 attackers against 3 defenders, without the offside rule, should be an attackers' win if they are moderately able.
As a consequence, a team defending a draw with eight or nine defenders and one or two forwards won't be able to win in a Collective Penalty shootout. Tactics would change accordingly and even weaker teams would be forced to try scoring before the shootouts. This will probably improve the game.

