I heard that the next version of Bitcoin Core will support HD wallets.
What will be the path used for that implementation?
0.13 (current most recent release) supports HD wallets (if you create a new wallet with 0.13 it will use HD by default, <0.13 wallets will keep the non HDness).
You can disable the HD feature in >=0.13 with
It does use only hardened private key derivation.
The keypath-scheme is
BIP44 is not supported right now. It makes little sense (weak security) to use public key derivation (BIP44 does) together with a possibility to export private keys.