Traditionally, Hollywood (run by angry liberals) and the Republican Party are hostile, so this shift is more of politics reverting to the mean. The main reason GOP members were on SOPA was the support of Nashville and the NFL.
This shift is a very positive development, it means the bill is becoming impossible to pass in a Republican House (and where GOP Rep. Lamar Smith has discredited himself by leading fellow Republicans into the SOPA morass).
There's no real hostility between Hollywood the industry and the Republicans, just Hollywood the media spectacle. High-profile actors tend to be more liberal, but the Hollywood executives (the ones who actually "run" it) are typically moderate business-conservative type people, the same as most other places in big business. In fact they literally are the same people due to CEO churn, and definitely from the same social circles; e.g. NBC Universal's CEO was formerly Comcast's CEO, and is a personal friend of JPMorgan Chase's CEO.
The RIAA types are even more welcome in the Republican Party traditionally, due in part to Nashville as you mentioned, and in part due to the significant influence of first Sonny Bono and now his widow Mary in Congress.
If this is a regression to the mean, when was the mean ever in effect? In the 1980s, Ronald Reagan maintained strong ties with Hollywood (even with people like Lew Wasserman who were active in the Democratic Party) and promoted their interests; in the 1990s, the GOP led the charge for the DMCA and Sonny Bono Copyright Extension Act. Arguably there was strong hostility in the 1950s-70s, when Joseph McCarthy thought Hollywood was full of Communists, and Nixon complained about it being controlled by Jewish Democrats, but that was a while ago, and for reasons (paranoia about Jews and Communists) that hopefully aren't going to recur.
This shift is a very positive development, it means the bill is becoming impossible to pass in a Republican House (and where GOP Rep. Lamar Smith has discredited himself by leading fellow Republicans into the SOPA morass).