Most shareholders don't hold individual stocks for years and years anymore. The companies you feel you do that with (I have Berkshire Hathaway and Apple among my few individual stock holdings in my retirement account, and neither has been touched in over a decade) are few and far between.
To the extent that shareholders are taking a "buy and hold" attitude on DXC shares they might get screwed due to such short term thinking, but if they have a short term attitude about DXC they'll sell them and move on to someone else before they really tank. The people who will get shafted are those who hold DXC shares for a long time - I wonder to what extent long time employees hold DXC shares? Hopefully they can easily invest their retirement accounts elsewhere, and if they are awarded DXC stock/options they don't have to hold them too long before they're able to sell.