After the end of this month, in order to get the ATP you will have to have 1500 hours, including the specific types of time listed in Part 61 (Instrument, Night, Night Takeoff & Landings, Cross Country, etc), AND complete an approved ATP training course, including 6 hours of training in a Level D Simulator of an airplane with a gross weight of 40,000 pounds or more, prior to being eligible to take the ATP written.
If you want to get a Restricted ATP, which will allow you to serve as SIC on Part 121 flights, you can get one prior to the end of the month with a combination of qualifications, including:
1500 Hours
or
1000 Hours & a Bachelor's Degree in Aviation Science from an approved university which includes completion of Commercial and Instrument from their approved 141 program.
or
750 Hours & Military Pilot
or
1350 Hours & an Associate's Degree in Aviation Science from an approved university which includes completion of Commercial and Instrument from their approved 141 program.
After the date-cutoff, applicants seeking a Restricted ATP will still have to complete the training course prior to being eligible to take the ATP written.
The new regulations do not affect the practical tests, only the written. In other words, if you took the ATP written now, you would have 24 calendar months to take the practical under the old rules, assuming you meet the above qualifications, and could avoid the costly ATP training program.
If you want to confirm what I've said (typed, not copy & pasted from some blog or website), open up FAR Part 61 yourself and begin reading. It's not rocket science (close, but not exactly) and there is a table of contents to help you find exactly what you're looking for.
Hope this helps.