George you obviously have as much respect fro American football as i have for darts. The differance between us is I can accept a dart player has a skill that many find thrilling. Unfortunately you see American football as a threat and are set to attack it at every opportunity.
As for ripping up the turf at wembley the grass is not settled as yet and is unlikely to be for another six months. Google old trafford if you are that interested, i think you'll find they're pitch has been relayed at least three times this year because of the same problem. However if they had gone the same way as many teams they would have a semi artificial pitch such as the Emirates stadium at Arsenal.
Incidently the New york giants had more Brits in their superbowl winning team this weekend than Arsenal. Although the viewing figures aren't out as yet i'd be willing to bet the superbowl had more viewers than match of the day.
American football is not a threat to football, rugby or any other sport in the UK, but with the money being pumped in from America it can't be written off. Take a look at the teenagers and what they're wearing.
As for your statement that it's warfare on grass .... As an ex soldier who has been in battle who understands the planning and skill level of our armed forces i think that's an excellent description.