For me my current Tivo (the two tuner TiVo Premiere with upgraded HDD) is very much the same box as what I got with the Series2 DirecTV unit back in late 2002 (I think it was then) in terms of features that I use.
The Premiere is way under powered in terms of CPU, something that I hope the 5th gen will resolve by moving the Stream encoding capability internally. But I still don't see Tivo supporting Chromecast, they'd much prefer to sell you a Mini for your TV.