In the sims 3: into the future, I bought a house in Oasis Landing (the future era). Now is there any way I can sell the present house and live in the future forever? (giving that I put a time portal in some public venue like the park or something)
No, since you can't be homeless in a map and if you sold your present home you'd be homeless in that map. The best you can do is minimize the money spent by buying the cheapest empty lot and then heading to the future.
You will however need to add the missing important buildings, like schools, since otherwise your kids will have random 4th and 5th traits due to no education. And there's only 4 jobs available in the future normally, so you'd probably want to add some other job buildings as well just for sake of variety.