Any form of communication, from cave drawings to Twitter, takes two to tango. . .an adept sender of the communication, and people who are prepared and willing to receive it.
I could be wrong about this, but looking at the core demographics of the two parties, it seems to me that the Democrats probably have the edge when it comes to folks who are routine users of digital pathways. The Dems skew younger and better educated (which in this country isn't necessarily saying much), while the GOP skews older and less well educated.
So no matter how much digital catch-up the Republicans are able to pull off at the sending end, they may still have fewer people at the other end of the pipe. . .the rest will still need to get their propaganda via mail and TV.