I think it is a good assumption that there will be many layoffs especially when it comes to card services. There is a lot of redundancy in that business unit since the Fiserv card service product (a FD product) was primarily used Internationally by First Data while the First Data domestic product is a behemoth in the US. They will sunset the use of the product Fiserv uses and convert to the other product. This will highlight a ton of redundancy. Its just a matter of time.
And lets be honest, both companies have reputations of laying off. Thankfully the Fiserv severance package is a lot better than the one at First Data.
On point post from @11w5CpUw-dna.