You're asking for everything. The closest you'll get to all is with m43. Light wildlife means at least 200mm 35mm equivalent lens, with m43 you get that already with 100mm. It won't be stellar, though, but you won't find anything light that will be. Vid should be, Panasonic body for best vid, make sure it's got body stabilization so you can use Olympus telephotos on it, that should save you some weight. Or again make some compromises with em10iii, not best vid features but it is 4k, not that heavy and pricey. You're loosing good night performance, somewhat manageable with fast lenses, but you'll have to make compromises. You won't get everything you wish for in one system. Look at alternatives as well. Fujis have heavy metal lenses, bit larger sensor helps in light. Sony apsc, will require looking elsewhere for quality glass, and that means Sigma which is heavy. For ff cams you'll have to ditch long range. Pentax k70 looks attractive as well, It's practically mirrorless size, fully weather sealed, definitely something I'd look at if I'm buying now. I know little of that system, so can't help you there.