Expedia's President had identified rail as part of their expansion strategy at the PhoCusWright conference in Fort Lauderdale back in November 2015. Rail is a more frequent purchase than flights or holidays, so it can drive more loyalty and regular visits to Expedia's website. 

Rail has suffered from legacy booking systems more than most sectors in travel. It will be interesting to see how far SilverRail gets integrated in to Expedia  or whether it operates as stand alone business. 

Ebookers/Orbitz was consolidated rapidly with few staff being retained, but other acquisitions such as Trivago and HomeAway which are different from Expedia's core offering have been allowed to operate independently.