Are microtransactions new? Last I heard they were going to put a monthly cap on the UEC players could buy with real money.
Secondly, microtransactions? Microtransactions don't generate anywhere near as much income as ship sales. Halo 5 earned $500,000 in a week after launch, when players were the most active, but even that number has dwindled as the the game's hype has died down. This is completely ignoring the fact that Halo players massively outnumber SC players. I'd be surprised if SC could raise even 10% of that amount through microtransactions, unless the microtransactions were priced so high that they were basically just ship sales by another name (Halo 5 has this problem too. There's nothing micro about a $25 transaction), and then that would just put them right up there with games like FarmVille, Candy Crush and other titles famous for exploiting players through shallow but addicting gameplay (and SC isn't even that addicting atm, just shallow).
CIG data shows that They have just over 1.2 million accounts registered. If we assume ship sales didn't exist and that the game was sold at a flat rate of $60 per person, and that 80% of those accounts are real people willing to pay that price (even including players who got into SC at prices lower than $60 and hence might not be willing to pay that price in reality) they wouldn't even have hit $60 million yet. Ship (or addon sales in general) have accounted for over 50% of the income they've received. They've raised over a million dollars in a day thanks to ship sales.
How many people are they going to fire if they're going to limit themselves to microtransactions? Right now they've just moved AI in-house, need to design over 90 more star systems, complete their netcode overhauls, finish producing over 15 more ships, redesign earlier ships to meet new standards, implement features including but not limited to mining, cargo, repair, FPS, and then debug and optimize the game. They're probably not going to be firing people after SQ42 is out, and if they pull an Elite and do a barebones PU release, who's going to add the remaining features if they've all been fired? Assuming they halve their staff it'd still cost them around $2 million a month in wages alone, a number that even the pledge campaign has had trouble keeping up with at times.
Microtransactions and lay-offs aren't viable, and really, if you were in charge of taking care of 100 workers and their office space, how would you raise $2 million per month every month?