September closings have started. Right now it's just the Howell store, but I think this might be just the beginning. The store will go when the lease is up at the end of the year.
https://www.app.com/story/money/business/main-street/whats-going-there/2018/09/13/barnes-noble-howell-store-closing/1283365002/
Generally, the company's been closing underperforming stores when the lease ends and the real estate people in NYC are unable to beat up the landlords enough to get a good deal to reup the lease. This is normal business--if the underperforming store is in a shopping center/mall with a lot of vacancies (particularly anchors) the landlord will either cut the rent or give kickbacks to keep other tenants from leaving.
I have no idea if this is the case in this case, but one store closing shouldn't be an indication of a larger trend--at least, not yet.