As Boston is New England's downtown and commerce center, Portland is Maine's downtown and commerce center. Boston embraces it and shows its influence outside of New England. Many in Portland just want it to remain a small city by the sea and the interior of Maine doesn't want to acknowledge the role Portland does/can play. Greater Portland needs to figure out what it wants to be when it grows up, even if it's 300+ years old. That will take strong civic leadership, foresight, and tough decisions, which don't seem to be on any display.
The metro area is well over 500,000 in population. Come up with a plan for how the region will grow to and accommodate 750,000. Call it the 750k Plan or something catchy. Signal to the businesses in Maine and beyond that the intent is for the region to grow in an orderly fashion, invest in & develop infrastructure, and economic opportunity for Maine. That would also send a message for higher education to invest in the region as the need and growing labor pool would follow. Universities will feed off that synergy and activity as they have around the country. Maine has the natural resources to support the growth and you can have a plan with plenty of public involvement on where and how to grow. Such as do you want to promote additional sprawl or do you want to identify and create economic and activity nodes around Greater Portland that focus on higher density residential, vertical development and transit options. It will do it on it's own as we've seen with limited success, but identify and plan for it.
Perhaps the City of Portland could develop a Peninsula Plan, or similar, where you identify how to add 5,000 (or another total) housing units on the peninsula and how you plan to connect them. Public involvement can determine methods, housing types, address long-term homelessness goals, and maybe expand going above 18-stories and where to locate that. The office tower needs will be on hiatus but the need won't disappear and the mix of uses can all support the downtown and peninsula, build the tax base, and work to reduce the non-profit tax-exempt parcels.
Now, this being Maine this would be tough for many to entertain, but positive growth and evolution can result from being in comfortably uncomfortable situations. Greater Portland's population will continue to grow with no plan or serious discussion, why not be pro-active and go on offense for a change rather than continuously having to be reactive and playing from behind as political inactivity and lack of will paralyze and set the city back?