It has taken 4 years since LTE was launched in Germany for the necessary bits and pieces to come into place to launch LTE roaming. But it has finally happened a couple of weeks ago. When I arrived in southern France I was greeted by an "LTE" logo in the display when I switched-on my phone after the plane landed in Marseille.
Sure, nobody was in a hurry to get LTE roaming in place as 3G networks still provide more than adequate speeds in Europe and roaming prices were and still are to a large degree prohibitive when it comes to 'really' using LTE, i.e. downloading tons of data at amazing speeds. But I won't complain, it's here now, roaming prices are falling and I'm looking forward to see the "LTE" logo much more often now when traveling.
You are, of course speaking from a Euro perspective. LTE roaming has been in place for years in the US.