The new Audi S1 sportback has already been unveiled, which has also the new front and rear facia. The old Audi A1 Quattro was the replacement for a RS1, but now it is not sold anymore and there is a gap in the lineup.
The rumours of the Audi RS1 with quattro 4 wheel drive standard. The RS1 will have, according to the rumours, a 2.0l engine, which can also be found in the Golf GTI and several other VAG products. It will also produce more than 231 hp which the S1 already produces.
Source: designrm.wordpress.com