From what I understand, Virgin still wants to use TiVo for the backend and data and use the Horizon User Interface on top of it, from what I heard Liberty Global are working with TiVo in order to do this.
https://www.multichannel.com/blog/vi...-report-418549
Knowing that Liberty Global have been mass-selling their European assets to Vodafone and to other companies (also Liberty and Vodafone co-owns Vodafone Ziggo in the Netherlands), it seems that Horizon's software (as in the backend that powers the UI) could eventually be scrapped. The V6 box's remote has TiVo's patented thumbs up and thumbs down buttons and its said that the box will eventually use the new UI, so I don't think they're going to remove TiVo's key features. So Virgin will be able to incorporate Amazon's library in the search as only the "shell" of the software and how its presented will be changed.
It seems that Liberty Global want to focus on the UK and Irish market, selling most of the European assets and the funds raised from the transaction will allow them to expand Virgin's network.