I don't think it will be built there. I can't know for sure how this will play out, but a stadium in Center City would just change the character of the downtown completely, and not in a positive way, IMO. I'm mostly familiar with MSG and that is an area I would avoid like the plague in NYC unless I had to ride transit. Lots of vagrants and cheap stores, fast food around it. (We already have that at Market East!!) But NYC is huge so go 8 blocks in each direction and the character completely changes. Philadelphia has a very small downtown from just river to river and put a behemoth like that in it and it won't be as easy to escape. But we'll see.

People complain about the area a lot but it's still better than it was in 2006/7 when I moved to Philly. I remember the first time coming out of Market East the year before moving to Philly with a friend who picked me up at the train station and being shocked at how rundown and creepy it was. (And I grew up in NYC so I know rundown and creepy). The area around the RTM and Convention Center was definitely NOT safe and I remember there being some publicized stabbings of tourists during some holiday event in the first few years that I was living in Philly. At first, I used to take the Chinatown bus (before the other buses) to commute a couple of nights between downtown Manhattan and Chinatown and I made it walking home each night around midnight but it was definitely sketchy. Sometimes the entire stretch under the Convention center street was filled with homeless sleeping on the sidewalk.

Crime, drug addicts and homelessness are the problems in the area, and until the CITY does something about that, you could put the Taj Majal there and it's still going to have repercussions.