Of course they've transformed. All successful terrorist groups do. What has really helped Al-Qaida in this effort is their linkage to Islam (radical or otherwise), which has a much wider appeal than the Marxist-Lenninist calls of most of the terror groups in the 1980s.

It's worth remembering that most of the terrorist groups that survived for the long haul (over ten years) had links to nationalist/ethnic minority causes (the ETA or PLO) or quasi-religious overtones or links (the IRA and UDA both come to mind). Any terrorist group that can link itself to something with pre-existing social value within a society or community has a much greater chance of surviving and thriving.