Having read through this a little and did a little research, I'm not going to even pretend to be an expert here as firstly I've never visited the stadium - much like AFC and secondly my main interest is Speedway so am not clued in to the Car and Greyhound history, but there are certain points that need addressing...
1. This is not a return to Plough Lane, AFC were formed in 2002 as a protest to the original Wimbledon moving to Milton Keynes, the original Wimbledon FC has a dissolved date as 2004, therefore AFC are not returning to Plough Lane
2. As others are pointing out Wimbledon moved away from and effectively kicked a sport out of it's national stadium - a grass pitch had to be laid which ended the chances of Hockey being played there. Since then the stadium has now been demolished and rebuilt. A lot of people turned there back on Wimbledon to AFC for this reason and it is painful to watch AFC now doing this to two other sports.
3. It has long been established that clubs usually only build a new stadium or redevelop existing one's when there is a demand for the extra capacity (eg, Arsenal, Manchester United, Chelsea etc) a side that averages a gate of 4000 on a good day doesn't need an 11,000 seater stadium, the rent levels could be crippling to the club as we saw with Coventry City over a period of time after they relocated to a new stadium that was bigger but after relegation there was no longer the demand for tickets led to problems with their stadium owners and money owed.
4. This also affects the local area, the two pubs mentioned by Teaboy probably have a large portion of their takings from days when Bangers are staged (and most probably Speedway as well). Whilst the stadium is worked on they will lose a large amount of their takings. Having worked in a pub, in the current economic climate there are not so many social drinkers due to the high costs of alcohol and also a shift in the generations and social activities. Not only the pubs though other local services will lose money from people coming to watch for the time being.
In conclusion, I feel this is a bad move for all parties. The local economy will lose regular income that came from the Bangers and Greyhound events, especially whilst the redevelopment especially AFC Wimbledon are taking a huge gamble here and if it fails it could be the end for them which personally I wouldn't like to see but I know a few who would. Lastly, all those decent folk from the Bangers, Greyhounds and Speedway who since 1928 have been flocking to Plough Lane and our now left just memories and a bitter taste at the way this has been handled.
But I would like to close with a plea to those few AFC fans who feel the need to dole out abuse about this, consider the points I've made and if you feel they are familiar that is because its how you would/should have felt when Wimbledon FC was ripped from your heart and home and sent up the M1...