There are about 1.75 billion smartphone users in the world and in the UK alone, 60.4% of them own and use a smartphone. This means that your website is likely to be seen on a mobile device than it was say, back in 2011 (over 30% of people used to use a smartphone).
We design all of our websites using responsive CSS, which means that whatever the size of your device, the layout ‘responds’ to give the user the best experience possible. This means that your website will remain functional even when new mobile devices were introduced in the future.
For an example, take a look at this website at different sizes (try resizing the window), or on a mobile phone.