WU charges ~ 10% to 15% to transfer money. This profit margin is possible because of the HUGE barriers to entry. Bitcoin (once widely adopted) vastly reduces that barrier. No barrier to entry means margins will collapse and WU will likely generate LESS revenue and probably lose market share to those willing to undercut them curther. When you consider today they are collective a massive premium, have a huge market share, and the cost for a traditional competitor to undercut them is massive, they have nothing to gain and a lot to lose.
They are in a similar situation as Blockbuster. Had Blockbuster embraced mail delivery (netflix) and kiosks (redbox) they would still be alive today. Less profitable, slimmer margins, likely would have had to close 70%+ of their stores and massive layoffs but they "could" have adapted. However the reality is that large, old companies are rarely innovative. They (like WU) really had no choice but they stuck with their core model and hoped things would change. Things didn't and they were crushed. In hindsight a smaller lower margin company is better than bankruptcy but business decisions aren't done in hindsight. Most "old tech" CEOs can't make that move to transistion the company to a future where they will see their market share, margins (and likely stock price) collapse. Inertia means they simply die out instead.
I don't see WU embracing Bitcoin (and seeing their margins be crushed to maybe 3% compared to 10% to 15%) until they have no choice. When they finally do move it may be like Blockbuster, too little, too late.