If no formal notice of abandonment has been approved by the STB, then the developers of Trump Tower would be in violation of federal statute if they removed track and didn't restore it. For an inactive line with no customers, this would be the only reason that anyone would spend money on repairing/rebuilding the track. Given a choice, most developers would rather rip it out because it makes construction easier, but if UP hasn't filed an abandonment petition there's not really a choice.
Look at the Chicago Terminal and Whole Foods on Kingsbury. The developer wanted to remove the track and had to file a notice of adverse abandonment over the railroad's protests before it could dismantle the track. In this case, there had been no business for years so CTRR didn't have a real defense, but it still required the STB to approve the petition before the developer could remove the track.
I have not heard any explanation from UP as to why it hasn't filed to abandon this line from the bridge east, but you can be sure sentimentality is not a factor. I think even in the 90's, most folks realized the line was living on borrowed time until the Sun-Times printing plant left...that was pretty much a guarantee because the plant was old and the land prices were going nowhere but up. Even the Tribune plant will probably move in 10 years. Now it's printing the Sun Times, Tribune, WSJ, and a few others. When property development in the near north side picks up again, the plant will probably relocate what's left of its business into the now-closed Sun-Times plant on the south side.
Soon enough, Finkl will be gone. UP has no traffic left on the North Line, the old Weber line is gone, and what's left of the Cragin sub has one bakery a few blocks north of the old crossing of the MILW. Not sure if Lee Lumber gets any cars at Avondale, and IIRC UP lost all the Beloit sand business to Avondale. Meyer down on the river has been getting stone by barge for decades. Sipi Metals doesn't really do anything with CTRR or UP anymore. About all that's left besides the bakery is Morton Salt, the Tribune, Big Bay, Blommer, General Iron, and possibly Metra for diesel fuel. Finkl is going to the south side. Aetna moved to a bigger facility on the west side, still on CP. UP fired the last customer on the Weber spur that hadn't gone out of business. Akzo became a redundant facility. I don't know what happened to the stone traffic at Avondale. The rest of the businesses just died off one by one.
In less than 5 years, you'll probably see UP lease everything at Clybourn to CTRR if CTRR doesn't give up first. If you look at what developers do with empty land and facilities down there, this trend is not recoverable. UP won't solicit traffic, and CTRR has such a poor property they've been unable to develop any new traffic. CTRR fought to keep its track on Kingsbury and Lakewood, but in fighting developers and the city, lost soundly on all counts because they couldn't demonstrate any traffic potential.
Urban railroading is a tough business.