^^^For me in these times new development isn't actually happening until it's happening (past sitework and onto physical construction). It no longer counts that you have something in the pipeline (metro Atlanta has thousands of units in the pipeline, but a historical low actually UC). You'll know something is financed when tower cranes or any kind of cranes are on site and a construction fence is up to keep passerby out.
FTR, there are a few developments UC right now near me that would not have penciled/gone up without city assistance of some sort. And to add, without giving away a private proforma, effective rents at a notably cheaper tower are modeled to be in the $1.80-$1.90 range on average. This tower received millions of dollars in tax credits and is going up at bare minimum expense on cheap land. The most expensive rentals in DT Jax I can find (by memory) were $1.25-$1.50/SF if that, and I don't know what the effective rents are because I don't know what concessions are offered.
The new construction garden apts going up in Raleigh-Durham are renting at $0.85-$1.05/SF effective. Due to the cost of land, all infill in Raleigh is either a hybrid, costing $135-$150K per unit and renting at $1.25-$1.50/SF or mid-rise apartments 8-10 floors costing $150K++ per unit and renting at $1.50-$2.00/SF. These numbers are rough and at the top of my head (I track that market among others for various reasons). Jacksonville can probably expect a mirror image of that situation, give or take negligible amounts.
I would say a hybrid stick/mid-rise infill in Brooklyn (like the one proposed by Pope & Land) would then fall in the $1.25-$1.50/SF rent category. So for studios you can expect to pay something like $800+ for 500 SF or $1,680++ for 1,400 SF 2+/2s. Look to Villas at St. Johns (institutional ownership - Atlanta based Gables), the most expensive apartments in town for some idea of pricing. The 1,323 SF floorplan is advertised at $1,940-$2,065, or well above $1.50/SF. The smaller units here appear to be cheaper ($1.17-$1.31/SF).
I would guess that 220 Riverside is better/concrete construction, it's more than 5 floors. Therefore I would guess it would rent for a weighted average of above $1.50/SF. You can sort of guestimate that 500 SF studios could rent for $900+ and 1,600 SF 3 BRs could rent for $2,300+. Look to Strand for indication (though I believe Strand is underpriced for original proforma...can't recall the history there and why it might be renting for much lower than a luxury high rise anywhere should be renting). Strand has a 2/2 1,343 SF unit advertised at $1,599 (could be higher, could be lower). That's $1.19/SF. The studios are by far the most expensive here, advertised at $1.80-$1.90/SF for 651 SF, you do the math. Though I must add those are huge studios!
The ultimate question is - can Jacksonville support the rents necessary to bring more expensive new construction out of the ground in infill areas? I think the "positive" numbers presented by DVI are positive for Jax, but overall I think the numbers for DT are comparatively weak (to a Raleigh or Charlotte or Nashville or Orlando or Tampa or even Birmingham).
A developer needs investors and debt, especially the latter. Jacksonville is no New York/San Francisco, where developers are stacking new speculative construction (office, condos, etc) with mostly equity and very little debt. It's hard enough to secure a construction loan or mezzanine debt in those proven strong markets, let alone a weak market like Jacksonville with no "proven" downtown submarket.
I'll definitely commend any group who can secure good solid debt to build in/near DT Jax, even with the uber popular multifamily product.