I don't think Hollywood has much to worry about, whilst Hollywood Stidos may bankroll a film, it doesn't mean that they are all filmed in Hollywood.
Off the top of my Head
SW 1, 4-6 shoot in the UK (2 and 3 had parts shoot in the UK) and 7 is likely to filmed in the UK
LOTR/The Hobbit, New Zealand
Harry Potter films shoot in the UK
Bond films shoot in the UK and around the world.
As for DW at 50 yearsold, I hardly think it's challanging Hollywood. The US like many other countries imports some TV shows.