A simple license agreement would stop Wine from having Win9x, if MicroSoft wanted to bar Linux rather than coopt it like the Borg.
What would releasing Win95 into open source accomplish for MicroSoft? It would give MicroSoft more desktops to sell MS Office and Age of Empires.
Right now, sole source proprietary hardward vendors like TiVo are limited to Linux or some flavors of Unix (ha, redundant statement) to ship a "free" OS with their DVR's.
Give them Win95 and then they can ship something that MicroSoft can charge for downloading games to.
So the plus side of releasing Win95, for MicroSoft, is that it will enlarge MicroSoft's market penetration.
The downside for MS not releasing Win95 is that MS constantly runs the risk that someone big such as Sony or Apple will figure out how to coopt the existing Linux marketspace, e.g. by either buying TiVo or by porting their games and applications to Linux...either of which would give Apple or Sony millions of new desktops to sell new software.
Does MicroSoft want to be the dominant home-tv-computer/business server vendor, or will MS delay long enough for another player to grab those markets?