I don't think that there can be two types of stock pricing competing for the same sector. At the start we were assured that Microstock would serve a different market, a market that could not afford the sort of prices available from traditional stock photo providers i.e.) church groups, very small businesses etc. I think this was always something of a mistruth on the part of the agencies even if believed by the micro suppliers. Otherwise there would have been a micro-use licence and there never has been.
What you call 'mid-stock' can have no future when major publishers can buy much the same content at 'micro-stock' prices. And once those prices become the established norm they are expected and demanded everywhere. At stock companies that offer exclusivity there is the occasional big sale as a possibility, almost rarity these days, because all publishers and all advertisers are under pressure with the demise of print media.
At a pub cricket match last week I met up with some senior publishers, one with a 'stable' of major international lifestyle/travel/fashion titles that we would all recognise by name. He almost pitied me when I told him that I was a stock photographer and really wondered how stock businesses stay afloat. He explained how simple it was to push for lower prices and play company against company and said that they really had to do this mercilessly because times were now so hard. He didn't think it likely that any of his major magazines would still be on sale in paper form in five years time.
I think what many find startling ( and annoying) is when those who have fully supported micro stock become disillusioned ( they see they are not making enough money despite being 'successful') and decide to convert to 'mid-stock' expecting it to have somehow survived in a parallel universe of high prices and buyers who have no notion of micro stock.
I have never sold a micro stock licence image in my life, never even placed an image as RF, but the writing is on the wall for all of us I fear.
It pains me to say it because I was predicting it and fearing it a decade ago but the micro model now seems inevitable for 95+% of stock uses. If that hasn't already happened.
Getty embracing micro-pricing models for its main collection was a huge turning point, an even bigger one for the future is Adobe Stock.
I truly hope that Alamy can stick it out and prosper with its uniquely encyclopaedic collection but where is the market space?