Seems doubtful to me. Yahoogroups is the only thing I use made by Yahoo, and they don't really "make" it as such. The content is all from other users. Yahoo hasn't done a good job monetizing it either. They happily send me a digest every so often which has no branding or ads or anything.
Clearly some sort of brilliant minimalist marketing strategy I don't comprehend.
My ISP converted all their email accounts over to Yahoo, but I don't exactly use Yahoo for that either. I have Gmail POP it. From my perspective, it's a Gmail account. And after that, it's an account with my ISP, not Yahoo.
For the others, well, never used Flickr. Once or twice used Yahoo auctions. Do they even still have them? Yahoo Japan auctions are good but that's not really the same company. Never used Tumblr. Had to stop and think, who was it again Yahoo bought. It's so irrelevant I paid it almost no attention.
Marissa Mayer DOES bother me, though. My boss has started emulating certain aspects of Ms. Mayer's work habits and compelling myself and fellow employees to follow along. That's great if you actually are a Marissa Mayer with huge responsibilities and commensurate compensation. But when you are a low-level mid-five-figure team lead for a software company which actively hates its customers and employees, these superboss work habits amount to jack shit. They don't fix anything at our level and they don't matter to anyone above you either, much less the executive team. Riding the team under you as if you are a Mayer when you are not is like watching whatshisname do his funky cowboy hop. It's not a real cowboy. My boss is not a real Marissa Mayer.