@Tiki Seem like it doesn't really matter that much but hey, why not, could actually make penality shoot-out more exciting (wich would be pretty hard). So, I'm not against but I don't really think its a useful change myself. Would rather have Fifa focussing on bringing up video replay at the top level of football as soon as possible.
Lets first explain what does it mean for the fewof us who doesn't know Tennis tie break rules.
Team A
Team B
If A is starting to shoot :
A-B
B-A
A-B...
Until a team does the break after 5 shots or more.
FIFA will experience it in Atm in women football, because they found tha statistically the team that starts shooting has more chance to win and less pressure ( arguably )
Statisticiens do not share this point as they consider mathematically both teams to have same mathematical chances but History proved that the first team to shoot has 55% to go through and the second 45%
( we consider that the number of PKs shoot outs based on is high enough that we consider teams shooting abilities, fans impact or teams form irrelevant )
Therefore with a team shooting once and then every team shooting twice in a row shoot twice so everyone could have match points in the hand of their keeper. Because in the actual shoot outs when you score first in the last PKs, your keeper has the game on his hands and the rival has everything to loose.
Im personally not against the idea, i think from my perspective you figured it out but I'd love to discuss it or hear people who prefer keeping actual format...
I would also love to put PKs in the PK box line. 10 meters far to make it as complicated to score as to save, to give good shooters and good keepers more chances to impact the outcome and less luck intervention. Also fact that it will be harder to score would make some excitement in scoring them.
During the game, it will depend on where on the box you get fouled to shoot the Pk, a far foul near the corner just inside the box do not have same importance than one preventing a goal 2 meters near the goal line. So having 2 shooting positions can't really be shocking imo And would prevent technical players from intentionally looking for the contact. But again that's another topic...