It would have been very interesting to see Final Fantasy 8 and 9 on the Sega Dreamcast back in the late 90’s.  During the Final Fantasy series was very popular especially after the momentum that the series had following the success of Final Fantasy 7 on the PS1.  Also, the Sega Dreamcast was probably at its peak in popularity during the late 90’s while having superior gameplay and graphics in comparison to the PS1.  

However, Square Enix seemed like they were have ton of success when Final Fantasy 7 soared in popularity in 1997.  At that point switching over from the PS1 to the Sega Dreamcast would not make to much sense.  Also, Square Enix had decided to work more with Sony opposed to Nintendo way before the Sega Dreamcast was released in 1998.  Even if Final Fantasy 8 & 9 was released for the Sega Dreamcast it would be hard to predict how well the game would do in terms of sales.