I think the coming of the new anti-piracy method used in GTA:LCS (and the the latest game "The Hustle : Detroit Streets" which has just been found to be using similar anti-piracy method) hints that the ISO honeymoon is going to END.
Many s have already done some thorough analysis on the ISO of GTA, and they all agree that the new protection scheme is NOT a simple version checkup like previous games, which can be very easily bypassed. In fact, there is possibly NO version checkup at all. The whole ISO is somewhat a new format - a format which can be read ONLY by 2.0. Many s believe that this is HARD to be cracked, possibly nothing easier than cracking the firmware itself. The s should already thank Sony for using just 2.0 so far, which is already partially cracked and this makes hacking easier. However, if Sony chooses to tie new games to 2.5 or even 3.0... you can already imagine how tough the situation will be.
Some think that hopes still remain on the future firmware launcher, which can launch 2.0 (or newer) firmware on 1.5 PERFECTLY. However, chance that we can have this any time soon is highly questionable (if it will ever be possible at all).
Conclusion? Even if there will still be ISO games for future titles, chance that you can get it right after (or even before) the release of the legit game is next to NONE. You may have to wait for at least a few weeks to play an ISO. Similar case applies to those who insist on playing legit UMD on 1.5. Personally, I do not see the point to play outdated and ONLY outdated games...