I believe the reason that people are concerned about the possibility of a delay is due to the Alternative Minimum Tax (AMT) and the efforts of the Congress to pass legislation to change the minimum income level before it kicks in. Without changes, it reverts back to the original income levels from when it was first passed, which is VERY low (it is not automatically adjusted for inflation & each year they've done a 1 year "fix" for it... but haven't agreed on a "fix" for this year as of this date).
As a result of all of that, the IRS has been saying that it may have to delay the ACCEPTANCE and the PROCESSING of tax refunds, as they say it takes (if memory serves me correctly) 7 weeks lead time to reprogram the computers, etc, & be ready to go with the corrected information.
How that will impact your refund timing and therefore your trip, I can't hazard a guess. All I can suggest is that you stay tuned to your favorite general news website for further updates.
Here's hoping that it won't have any effect on your vacation so that you may Enjoy the Magic!