I'm sure Serena will be at the Australian Open, the only problem is, Will her stomach have healed with enough time so that she is properly prepared for it?? meaning, did she get enough training, full out practice sessions etc.
If the Answer is yes, Im sure she will do fine.
I think Venus will also feel alot less pressure next year, and she seems extremely motivated to do well. I think in 2004 she wanted to quickly come back and dethrone the belgians to get back to the top where she was in 02-03 and put too much pressure on herself. Since she seems to be healthy, I really have a good feeling Venus will do very well next year, I see her getting back to the top.
As far as Serena, if she is healthy, then she's a given. She still has the BEST game in the WTA (very close with Venus tho) and it's still evident when watching her matches that she cares very much about tennis. If she starts off the year on the right track, doing well in the exhibitions against top players, she will get the confidence she needs to plow through the field in Australia.
I think Serena is extremley motivated to get back to #1, for in her mind she still is, and still considers herself "the best". Venus will do exactly the same, so I think 05 will be a very exciting year for them and their fans.
I Can't Wait!!