The tours need their autonomy. The ITF should be in a position where they could govern the sport, but unfortunately they don't have the necessary diversity amongst their leadership.
I don't lke the idea of more combined events. For one, someone often gets delegated to second-tier status (usually the women). For another, it dilutes the uniqueness of the Slams. If events were co-ed, the slams would only be "more of the same", with more players.
For those of you who weren't around for the dawn of the Open Era, this is actually how it was back then. Events were combined, men and women. Then the Open era came, and with it, prize money. What happened? The men made the big grab. They hogged the lion's share of the prize money, and the show courts. Women's matches were often scheduled in the early morning hours, and/or on courts so remote you need a Sherpa guide to find them. It wasn't until the women broke away to form their own tour that they made any progress. (The proverbial "straw that broke the camel's back" was a tournament that offered the men 8X the prize money of the women.)
The tennis community is still one of the most narrow-minded groups around (exceeded only by golf). I could easily see a similar situation evolving even now. One ATP guy remarked that he wishes they had enough money to buy the WTA Tour, so they could stick it away somewhere so they'd never hear of it again. Hardly makes them trustworthy enough to partner with. And consider that ITF officials come from ATP backgrounds. Doesn't exactly make it sound like they'd have everyone's best interests at heart.
The ITF could best help the sport in the promotional side. They should use some money to buy airtime on shows like SportsCenter, so tennis scores and highlights get shown daily. And everyone involved in tennis makes the same damn mistake: they run their commercials promoting their tour/sport during... tennis telecasts! Talk about a waste of money! The only people that see them are already watching. Run the commercials during popular events from other sports, like the NFL playoffs, the NCAA Championships, the Daytona 500, etc., even if they can't run them as often. Better yet, tailor the commercials to highlight various aspects of tennis that would appeal to fans of that particular sport.