Reuters' story mentions that Apple would take a 20% stake while Foxconn would own 30%. With Toshiba keeping a stake as well [1].
It's certainly not in Apple's interest to let this industry consolidate further [2]. Memory prices have already been on the rise and Apple is using more of it (that actually could be the reason why it's rising).
Over the past decade, the memory market has been flooded with cheap chips, causing most players in this market to lose value while breaking even or making a slim profit on memory sales.
Hopefully, Apple is planning to single source or majority source their memory through Toshiba, and give them funds to develop more advanced memory on newer processes, as that is what this market needs to develop further and faster. Apple may extend their engineering talent into building their own memory controller perhaps, similar to how they have done a ton of in house design for the ARM SoCs used in the iPhone/iPad lineup, instead of using off the shelf ARM designs.
Even if Apple invests in Toshiba's unit there's no way they're going to use them as a single source. They might give them a guaranteed percent of their NAND orders (especially if they get favorable pricing). It would still be in Apple's interest to shop around.
Also they already design memory controllers. They purchased the Israeli company Anobit in 2012 to do just that [1]. That's why Apple's storage benchmarks on recent products are really good.
I am surprised to hear the negative sentiment on the memory market as for most users who build computers don't always look for the high-end memory. In fact, I am not sure how much performance gain one get from a high-end RAM on a gaming system.
IIRC it can give a 30% to 40% performance boost on APU based systems, as the increased bandwidth to the GPU allows for much faster processing. Alternatively, Intel decided to put a few hundred megs of cache on their iGPU, which has made their graphics performance much better, and lessened the gains from increased Ram speed.
It's certainly not in Apple's interest to let this industry consolidate further [2]. Memory prices have already been on the rise and Apple is using more of it (that actually could be the reason why it's rising).
[1] http://www.reuters.com/article/us-toshiba-accounting-apple-i...
[2] https://www.statista.com/statistics/275886/market-share-held...