No. no no no. NO NO. In the words of Trent Reznor... "I do not want this."
If they do away with the 3.5mm jack and only have the Lightning connector then I can either charge my phone or listen to music... not both. Much in the same way the new MacBook only has one USB-C socket.
And they'll make the phone thinner, mark my words, instead of putting a larger battery in it.
I honestly at the moment can't see the benefit of slightly better audio being in any way even remotely commensurate with the drawbacks...