With just 30 days to go in the 2012-2013 TV season and the May sweep starting tomorrow, it seems this week we need to talk about the future as much as the past. The recent past is straightforward but full of shifts: Week 30 of the current season saw CBS remain No. 1 in overall viewership for an eighth week in a row but lose the adults 18-49 top spot after four weeks to Fox. But it was a very tight lead for News Corp-owned network for the week of April 15-21, with competition breathing down its neck. By competition, let’s be specific. Last week saw NBC’s Monday and Tuesday airings of The Voice prove just how dominant it has become by easily taking the two top spots in adults 18-49 (5.2 and 4.6, respectively) and in viewership (14.448 million and 14.155 million). That closed NBC right up on Fox. With a four-week demo high for the unsteady American Idol on Wednesday, a dip for Glee, growth for Hell’s Kitchen and a strong UFC on April 20, Fox pulled a 1.9/6 in the key demo. However, with The Voice’s results plus coverage from Boston of the marathon bombing and manhunt appearing in primetime throughout the week and lots of repeats overall, NBC tied with CBS in adults 18-49. The two were just behind Fox with a 1.8/4. Third place was also a tie, with ABC and Univision garnering a 1.4/4.

Here’s where it gets a bit sticky. Ratings and sharewise, Fox actually stayed in place from the previous frame, while CBS declined from its Week 29 2.4/7, NBC inched up from its 1.7/5 and ABC did the same from its 1.3.4. The CW rose a tad to 0.4/1 from the 0.3/1 it earned the week before. ABC was second in viewership with 6.62 million compared to CBS’ 8.26 million. Fox was third with 5.61 million and NBC was fourth with 5.56 million. Year-over-year, ABC’s demo rating was down 26% and its viewership down 14%. The CW fell 20% in the demo and 8% in its total audience. Compared with the same frame during the 2011-2012 season, Fox slid 14% in 18-49 and 19% in viewership. CBS stayed the same in the demo and was up 1% in viewership. NBC also went up, by 13% in adults 18-49 and 7% in viewership.

Related: ‘Big Bang Theory’ Repeat Beats ‘Idol’ Head-To-Head In Viewers For First Time

But things are about to get interesting. NBC is betting the house on The Voice over sweeps. Taking on rival Idol directly two weeks in a row on Wednesday, May 1 and Wednesday, May 8, the network is expanding the series to five hours of new programming and weekend repeats for Weeks 31-32. But after NBC’s dismal winter, how much can Voice really change things in the end? As thing stand now, with a 3.0/8 season to date, CBS looks poised to win this year in adults 18-49, adults 25-54 (3.9/10) and viewership (12.07 million). Which just goes to show again how much TV muscle sporting events like the Super Bowl, the NCAA Tournament and The Masters have. CBS had them all this year, plus The Big Bang Theory and old warriors like Survivor, CSI and NCIS.

Heading into the final stretch, Fox has a 2.5/7 season to date rating in adults 18-49, putting them in second place for the 2012-2013 season. Fox had held the top key demo for eight consecutive seasons beforehand, but as Idol went further into decline, The X Factor‘s Season 2 was down and new shows like Mob Doctor and Ben & Kate sank, it becomes clear that CBS is simply stronger on too many fronts and will snap that streak. Having said that, even with a bad year, Fox is still muscular enough to come in second place and no lower. So that leaves third and fourth place, which look to pretty much be what they were last year with NBC ahead of ABC. It is the spread that makes all the difference, and that’s where The Voice could actually play a role in the coming weeks. During the 2011-2012 season, NBC and ABC were almost tied in their 18-49 ratings. NBC also had a slight lead in viewers in the demo, drawing 3.21 million to ABC’s 3.14 million. In the 2010-2011 season ABC was third to NBC’s fourth and the year before that the two were tied. Season to date, ABC (with 7.843 million) is ahead in viewership over NBC (7.035 million) and Fox (7.078 million). However, in the 18-49 demo, NBC holds a 2.4/7 to ABC’s 2.2/6. As bad as NBC has had it until the return of Voice, they did have a good fall. Whereas ABC saw new shows like Last Resort, 666 Park Ave and the much-hyped Zero Hour go down, while new drama Red Widow lacks bite, Nashville is soft at best and reality show Splash is all wet. Even a vet like Modern Family has shown slippage and heavyweight Dancing With The Stars is way down. Then add to that two nights of The Voice for the rest of year.

No one said it was going to be pretty.