The line 8.Bb3 a5 9.0-0 d6 still occasionally occurs in games of IMs and GMs, and the results are actually quite ok for black. For example, Hou Yifan-Yu Yangyi, Kudrin-Diamant, Vishnu-Vazquez Igarza and Saric-Damaso.
However, at the highest level, it indeed seems that black is looking for alternatives. At the latest FIDE Grand Prix, Palma de Mallorca 2017, Gelfand tried 8....d5 against Vachier-Lagrave and 8....d6 against Vallejo Pons, but lost both games.
A remarkable alternative is 8....Re8, first played by Zvjaginsev in 2013. This move has been repeated in several GM games, e.g. Leko-Vitiugov and Sanal-Dubov.
EDIT: In the first round of the Gashimov Memorial 2018, the theoretical discussion on 8....Re8 is continued in the game Navara-Mamedov.
Recently, a new repertoire book has been published: The Hyper Accelerated Dragon by IM Raja Panjwani. According to a book review on Canadian Chess Newsfeed, the author analyzes two variations against 7.Bc4.
If White avoids the Maroczy (c2-c4), then the only other way to stop the ...d7-d5 equalizer is 7.Bc4, which is the subject of Chapters 2 and 3. Black could allow the game to transpose into a Yugoslav attack (Bc4, f3, Qd2, 000, and a kingside pawn storm) but Raja wants to avoid that, and offers two antidotes: 7...Qa5 (ch.2) and his own system ("My System") which is a hybrid of the Dragon on the kingside (e7, f7, g6, h7/h5) and a Taimanov on the queenside (...a6, ...b5, ...e6). That's the subject of Chapter 3, and the excerpt in the game player below.
1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 g6 5.Nc3 Bg7 6.Be3 Nf6 7.Bc4 O-O 8.Bb3 a5 (8...d5)(8...d6)(8...Re8) 9.O-O d6