With the departure of the Athletics essentially sealed, Oakland will have lost all three of its major league sports teams within a five year span. That leaves the city - situated in one of the US's largest markets - without any major league sports at all and may open the door for an expansion team to replace the A's.

There are plenty of roadblocks in the way. A franchise has just moved from Oakland because it was dissatisfied with the market and there is no guarantee a new franchise would find things any easier (although the problems the A's faced were in part because of the attitude of their ownership, which a new franchise would hopefully not replicate). It is not clear where an expansion franchise would play - unless it is a temporary home the Oakland Coliseum would be a non-starter, while the Athletics' departure was in large part because the team and city could not reach an agreement for a new ballpark. It might set a precedent that the owners' are wary of - implying that when a team leaves a market it can be quickly replaced with an expansion ballclub and so potentially reducing the owners' leverage in future negotiations with their own cities. And there may just be too much bad blood between MLB and the city of Oakland - and in particular Rob Manfred and Oakland mayor Sheng Tao, who have engaged in a public war of words - to make anything happen.[1]
 
But by the numbers Oakland is a strong market - even if the below data inflates its case because it is not the major city in its metropolitan area - and it successfully supported Major League Baseball for decades. It may well once again prove to be an attractive destination for an MLB franchise.