Alright, lemme don my asbestos undies. Here goes:
Yes, Fenway is the oldest ballpark in the majors. Yes, it is historic. But at the same time, it has the third-smallest capacity (only Tropicana and Oakland County are smaller) in a system with quite literally a HUGE fan base. When you consider the cost of going to a game (highest ticket prices in the majors) it becomes prohibitive, and that's assuming you can find any tickets anywhere near face-value, either on StubHub or at Ace Tickets. Access to the park sucks, parking is worse. The concession prices are sky-high compared to other ballparks.
Try taking a family of four to Fenway--EVER. Even if you managed to find four bleacher seats at face value (nearly impossible), you're already out $150-175 for tickets and parking, before you've ever stepped foot on Yawkey Way. How are you going to build a fan base where a trip to a game will bust the budget of most families? Have these people not heard what other clubs (who also sell out quite regularly) do to attract families? Sunday sales? $5 seats in the outfield (not possible with the Green Monster)? You can't realistically expect people to plunk down the equivalent of cable, electric, and phone for a month for three hours of watching guys chase a ball around.
Again, I know that Henry has NO intention of moving or building another ballpark near Foxborough or anywhere else, and Lucchino has said so. That being said, even with the renovations that have been put into the place, there's no way that stadium will last the 40-50 extra years they think it will last. Pay me now, or pay me later, so the expression goes. Would it make sense to build a sports megaplex down south? Meh--access to/from Gillette Stadium is bad enough already. Imagine it on a Sunday in September or October when both the Sox and Pats play. Out west, perhaps? Room to grow, certainly, but where? Worcester? Not even. North? Not enough of your fan base coming down from NH/ME.
Henry is walking a tightrope. Yes, Red Sox fans are indeed very lucky that Frank McCourt didn't get hold of the Sox and instead ran the Dodgers into the ground, but there are other reasons for the Dodger's failures which go beyond McCourt's mismanagement and divorce. However, you can't count on putting an LCS/WS contender on the field EVERY year. There are going to be dry spells. What happens when, as in the 1980's, you can't get even 20K at Fenway?
The biggest issues I see:
(Leave Fenway as is):
--Historic ballpark
--Already well developed
--Year round use for concerts, hockey, etc.
(Moving/rebuilding Fenway):
--Increasing stadium size (ticket revenues can pay for cost of new stadium as long as attendance doesn't become an issue)
--Access
--Affordability to average fan
Bottom line, you're not going to make everyone happy, regardless.