A chunk of what will be determining things, I suspect, is what has been choking the 'lots of small ships' crew.
Ship construction has proven to be limited by strategic materials, not raw cost. Penny-pinching isn't getting anywhere, number of hulls is more limited by how many Warp Cores Starfleet can make from their supply of Dilithium, how many torpedoes are available per hull, and other strategic resource concerns.
Which means that optimal cost-maximizing is actually to maximize the amount of ship mobilized per ton of Warp Core built. Which means bigger ships with more equipment are in, small specialists are out. Fewer, higher-quality ships, rather than bunches of cheap but ineffective Newtons. Raw cost is still some concern, but we want to build every ship out to the full potential of its warp equipment, not trim down the ship to squeeze out a bit of savings. More of a concern is that we can't waste our limited supply of strategics on ships that are too easy to lose, repairing and refitting saves that precious Warp Core.