Hi Otava
Yes, for 4K you will need a new "engine". The more RAM you can afford the better, at least 16gbs, 32 if possible. And if you can stretch to it, at the very least, an i5* processor, in fact an i7* is better altogether *or the equivilent. My i7 has built in graphics so I don't have a graphics card, so I cant advise you on that.
Even with all this you may find it is a struggle to edit and you may still have to resort to shadow files or another proxy method.
And then you must consider how you are going to store and view your projects. 4k video files are large, take up a lot of room on storage disks. To get the best viewing quality you will need a 4K TV or perhaps a 4K PC monitor. There very few 4K media players that handle more than 30fps.
Think carefully before you make any decisions about what you buy, try and future proof a bit by getting more than you actually need. It's better to have too much power than not enough and getting it spot on, almost impossible.
Is 4k worth the hassle and expense? My opinion, absolutely YES. The quality is wonderful, even when downsized to 1920X1080.
Go for it, but don't try to cut corners.
Panny TM10, GH2, GH4,