Not sure,but if gaara opens sand underneath,and does his dessert requiem,obito would really have to escape that. If obito uses kamui,anything touching him(shit load of sand) would be warped with whether he likes it or not,so if he warps into his dimenion,then much of the sand would follow him,and could still fall on himxd.
@ the guy saying paper bombs were hurting him,untrue,he can't be intanguble and warp away at the same time,he was intangible through out the explosions,so he couldnt warp,if he stopped being intangible,then he wouldnt have had any time to warp himself,seeing as the bombs would hit him,and warping himself takes longer than warping something else IIRC. However,if tobi is tricked into warping a sand clone,and he accidentaly goes back therexd,we will have not a rasengan,but a sand pyramid on his face
