When next gen begins, BD will be dirt cheap, and whatever game needing more than one DVD will be cheaper to put on a single BD. Most probably Ninty will use the BD HW base and physical disc, but with a proprietary data format, to pay almost no royalties to BD consortium.
About royalties, both BD and HD-DVD use the same two main video formats, one of which was developed by MS that released it for free, but still owns one of the most used codecs for it, so MS too indirectly gathers a small chunk of royalties from BD. MS pushed HD-DVD before its death because it owned the most used implementation (*) of its interactive contents and because despite not being overwhelming, Sony is one of the biggest members of BD consortium, and finally also because BD interactive contents are based on a Java derivative, that MS hates, besides not earning a cent from it. Now that HD-DVD is dead, MS can bite the bullet and accept BD, it will gather its small chunk of royalties, smaller than what it could get from HD-DVD, but better than nothing, and enjoy economies of scale, as many correctly pointed out, and the convenience of the bigger space available, and it will gather a small satisfaction too, that Sony bore most of the financial efforts to launch BD and bring it down to mass market affordability, also losing consoles leadership due to the excessive price it initially forced PS3 to have.
(*) (based on WinCE, IIRC)
