...What would've changed in terms of...
1)Sales
2)Consoles lifespan
3)Games Released for the System
4)The Consoles Successor
5)Anything else you think would have changed...

For Me:
1)I would probably say the only change really wouild be the PS2's Dominance over the Console Market... I would probably say...
Dreamcast - 6~7Mil. (It wouldn't have had a year with no opposition to face... And with PS1's Popularity, the Dreamcast would've had an even worse chance of succeeding. It also would challenged in the Online market by the XBox)
PlayStation 2 - 75~80Mil. (People sick of waiting for Nintendo and the New "XBox" would have their consoles, and the PS2 wouldn't have a head start, GTA would be shared with XBox. However it would still win the generation,  a built in DVD player would help with that...)
Gamecube - 35~40 Mil. (Would do better, but not by much... The over popularity of GTA, and it not being on the system would still do a lot of Damage)
XBox - 65~70Mil. (The sheer selling power of GTA would be shared with the XBox, It would dwarf the Gamecube, and nearly catch the PS2. Online would greatly improve its chances.)

2) I'll do the rest of mine later,I'm late for something right now...

Looking forward to your opinions! ...and NO TROLLING!

So your answers are (approximately)

Dreamcast -40%
PS2 -33%
GC +70%
Xbox + 275%

I really doubt the Xbox would have had that much of a boost

The problem with this topic is that there would be no point in releasing Dreamcast as it was in 2000-2001. DC came out in 1998...Xbox/GC in 2001...3 year gap is huge in gaming.

Better topic would be "What if PS2,GC and Xbox came out at the same time?"

If that was the case

PS2 - 75mil
GC - 35 mil
Xbox - 50 mil

Playstation brand was too much to ignore.

PS2 would have still dominated. Coming off the successful PS1, Backwards Compatiblity (which was really never done up to this point successfully) and a built in DVD player made it a big draw for a lot people. Dreamcast and Gamecube still would have faced lack of third party support and a troubling past of systems that didn't live up to expectations. Xbox would have done better but there would have been a lot developers still half hazardly putting games on the system. Publishers didn't come around until they worked out better deals with Microsoft. Don't forget many companies like EA didn't like how Microsoft was doing business and how controlling they were (online was one thing that came to mind).

If anything, the market might have imploded on its self and consumer backlash due to not knowing for sure what system to actually get.