If all excanges adopt sportsbooks what will be the pros and cons, a friendly un-bias open debate

With the other place adopting a sports book and betfair hinting at one many times, what will be the pros and cons
for instance can all bets be hedged in there own exchanges if say someone puts 1000 bets on a greyhound in a market at purple that is less than a thousand pounds, how can they hedge it?

Will exchangers lay the bet and thus force the rejection of persistent winners?

What do you think up-shot will beof having books for backing only will have in an exchange environment?

Please betfair don't take this thread down as we are all curious, thank you