T.---Unfortunately your SIL must be the one to draw the line for her son. He MUST get a job/get into school or he is OUT. Then she has to stick to her guns, or else he will be living with her forever.
My neighbor has the same situation although I don't think she minds her son still living at home. But he is miserable...few friends, unable to socialize and he just won't do anything. It's so sad...I keep thinking why would she not want her son to have a LIFE. It is up to her to push him out of the nest...for his own good.
And don't get me started about my parents and my brother. He will be 53 this weekend and is at home. My parents want him gone but they won't kick him out...I'm sure because it would require getting police involved...and he has had problems with drugs and the law in the past. It's such a sad codependency. My parents will never be rid of him because they didn't make the really hard choices when he was younger.
My husband threatened our now 25 year old son about 6 years ago. Get a job, get into school or get out. We had just moved 5 hours from where he grew up a year after his HS graduation. He had gone to college one year but failed there. Not because he wasn't capable...he just chose not to be. He ended up getting a full-time job at Walgreens (a great company to work for if you don't mind retail...and they are always looking for and hiring reliable people...they offer insurance and profit sharing benefits that are unheard of in this economic climate) and is now a store manager making a lot of money for a 25 year old.
It really is about tough love. Your SIL needs to let her son know that she will support him in anyway and at all times...AS LONG AS HE IS TRULY TRYING TO DO SOMETHING. Otherwise, he is out. He needs to wake up and hopefully it won't take something traumatic to do that.
I'd have to say it's probably not a good idea for you to take him in but it could be an option depending on a whole bunch of different things. With your hubby gone, it would be harder. You didn't say, but it sounds like your nephew doesn't have a male role model currently. Having that could be helpful but...
Good luck. It's a really tough situation to be in. One last thought. Your SIL and nephew should be in counseling to get to the bottom of his issues. That could help as well. Saying my prayers...D.