@Shaun Peterson Hey Shaun, I think the simple answer to your original question about Lincoln Terrace is that people are discovering the value of renovating older homes that are very close to everything. Similar style, but half the price (or less) of something comparable west of 235.
From an investment perspective, most analysis starts with determining an ARV. While it's easy to speculate that a fully-rehabbed house will be worth more than an early-to-mid-1900's built house in distressed condition, it can be harder to prove on paper. You need to be well-capitalized in order to be a first-mover in a transitioning area. Once there has been some verifiable rehab and / or new build activity, that entices other investors who can borrow money based on the sold comps. in the area. Comps. also help owner-occupant buyers in terms of properties receiving favorable appraisals.
One issue with the house on 14th is that there's no garage (as far as I can tell). Appears to be an above-average rehab otherwise. (Photos can be misleading; especially with older homes.)
I agree with Rhett that in older neighborhoods like Lincoln Terrace, there can be a sizable elderly population and a full transition will take time due to father time.
In regards to JFK, an area I'm very familiar with, it will be interesting to see what happens over the next few years. The area has already changed drastically yet slowly over the past 15 years. With the opening of the Page Woodson School redevelopment and construction of townhome-style properties nearby, there's a ton of new development in the area.
Construction cost to build something modern would depend on the builder, but would be in the $110 - $200+ / square foot range depending on finishes. I have a builder contact I can refer to you.