If the rb was left with relatively low mods and used as a daily theres no reason why it will break for a very long time, probably longer than the fords and holdens. All you have to look at is rb30 bottom ends over 20 year old motors with 3-400,000 on them and people still just slap them into there hybrid rb builds and pump out 300-350kw still reliably.
Even rb25 from r33's are now 15-20 years old and still go strong running 300kw plus. Theres no chance youll get a ford or holden engine thats 20years old with some km's on it that will take double its power.