As this develops, there seems to be 5 cities that are concluded to be the 4 expansion cities and a relocation target for Brampton. Cornwall, Chatham, Niagara Fall (NY), Oakville and Vaughn are the 5 cities. I am not sold on 4 of these.
Cornwall - I have the least concern about Cornwall. They have an arena, but it does need updates. They had a successful run with the Aces in the 70s and 80s. When they upgrade their arena, this has the makings of a successful franchise. The biggest downside is its location. It is on the periphery of the league's footprint. However, there will always be teams on the periphery. Soo, Saginaw, Erie and Ottawa fall into that category and are all successful. Cornwall does fit well with Ottawa and Kingston.
Chatham - They need an arena, but plans for a new arena are slowly moving forward. I question the size of the area and the fact that they have teams that are in close proximity to 3 other OHL teams. Their fanbase will be primarily Kent County which is limited and some of those people are already Sarnia, London or Windsor fans. These fans may become Chatham fans, or they may stay loyal to the teams that they already follow.
Niagara Falls (NY) - St. Catherines has a team and is less than 20 miles away, so I have a concern that they will get little support form Niagara Falls, Ont. Niagara Falls (Ont) has lost several teams due to lack of support. I believe that Sudbury, Saginaw and Erie were all once in Niagara Falls. The question is will Buffalo support this team. Buffalo has an NHL team and cities with major league teams often do not support Junior Hockey.
Vaughn and Oakville - I will address these two together. My question is the mindset of the population in each of these cities. These cities are similar to Brampton, Mississauga and Plymouth. They are suburbs of a large city with an NHL team. Oshawa falls into the same situation, but the people of Oshawa see themselves as part of Oshawa and not the GTA. Oshawa takes pride in supporting the Generals. Plymouth was never successful because people living in Plymouth see themselves as part of a major city and not part of the smaller suburb. If someone in Plymouth said they were going to the hockey game, they were talking the Red Wings not the Whalers. I don't have a feel for how this will work out. If they have the Oshawa scenario, they will be very successful.
I have a problem finding any additional viable cities. Thunder Bay doesn't fit geographically, and every possible US city has a USHL team of a pro team.