I think it is good that we have veteran leadership at the helm of D&D at a time of great change. When I first heard the news about 4th, I was very apprehensive. If they just evolved the game like what happened between 1E & 2E, and 3e & 3.5e, then it would not be worth it. Having kept up on all the news of 4e, I can see where a new edition had to come out.
The d20 industry has made great strides in mechanics and concepts. WOTC and third party publishers fundamentally changed the play style of d20 gaming. Their where beginning to be a lot of play options that where faster, more fun than what core D&D could provide (ex. Castles and Crusades, True20, Iron Heroes, BO9S, Complete Arcane, etc.) without a lot of extra work on the individuals part. Play styles have changed with technology too. Groups are getting together from diverse geographic locations via the internet, and technology is starting to infiltrate the sit down game session. The technology driving this is very fragmented; theirs not a definitive product that sets the standard. Their are a lot of high standards in the products offered, however. All of these factors begged for a new edition that sets the standard once again, that provides the vision to wrap these factors into one distinct product. D&D has always been the industry standard, and if WOTC did not act and kept complacent, it would only fracture the industry more.
In times of great change in any segment of society, it is good to have solid leadership at the top with vision for the future. Unlike other times in D&D history, I think we have the right veteran leadership for our industry at the time we need it. At the time of 1e vs. 2e upgrade, the leadership of TSR was fundamentally in turmoil, and it is hard to get visionary products in a situation like that. What you get from that is a product that evolves in a linear fashion. I think a lot of people would agree that 1e to 2e was not much of an upgrade when it came down to it.
Going from 2E to 3E was revolutionary change for the time, and it accomplished the goal of consolidating and expanding the player base, and setting the industry standard again. The leadership at that time was not in turmoil; these where veteran RPG designers, players, and editors that have a love for D&D.
The changes from 3e to 3.5e where not very significant in the grand scheme of things. Mostly, in my opinion, it was a change born of the desire for most designers and players to tweak things. It also served the purpose of keeping the game vital. Changes have to be made in a hobby like ours every so often or things go stale. It's not like Monopoly where one rules set will suffice for generations.
Going into to 4e we have the essentially the same leadership that put D&D back in prominence. As an industry, I think we have the best team available for our future. In the next 5 years this industry is going to change drastically, without or without WOTC or D&D leading the way. I am glad they have chosen to lead and lead in a visionary manner.
As an aside, my favorite version of D&D is the Moldvay/Cook Basic/Expert edition. I liked and played both 1E and 2E. I never did play 3e. Life did not have me in RPG's at that time. I got back in with 3.5e, and at first liked it but began to hate it from a DM's stand point. This eventually got me looking at other games like Castles and Crusades (great game!) because I longed for simple DM'ing. I live near a college, however, and to keep my gaming group vibrant and full of players, I really had to play 3.5e because that is what all the new gamers where coming in under. They wanted to play D&D. They did not want to play other games. My love of playing the game outweighed my detest of the rules set. I learned to lump it and like it. I want my D&D K.I.S.S.'ed (Keep it simple stupid). On the other hand, I have learned from my young players that having player options can really be groovy! I do not have to think about player options, my job is to think about plot, monsters, and NPC's and make them go at a good pace. In reading the design philosophy behind 4E, it really makes me harken back to the spirit of the Moldvay/Cook edition (simple play) with a modern gaming sense about it (good mathematics, lots of player options, and the ability to manage the backend resources of the game in a K.I.S.S. manner).
Do I have concerns about the new edition? Yes, but I trust in the people we have working on the game to do the best job they can for the love of the game. Is the game going to be different? Absolutely.