Not necessarily antennas. Antennas are in physical layer, not transport or network layer. 802.11n can have multiple antennas but if you are at the boundary of the coverage, multiple antennas won't help much. Multi-path TCP is more about multiple transport streams. Of course it would require separate antennas for Wi-Fi and 4G but that's already the case on current mobile devices. So nothing changes in this sense. It won't affect battery life much from aspect of antenna power consumption because you can only set 4G to backup link, and MPTCP won't offload to 4G until Wi-Fi is not responsive. If you are using full MPTCP (using two links all the time), then that's the tradeoff between performance and power consumption.