That is unless you live in an area that receives programming from a low power, class A or translator station. Then you would still receive signals from those stations as long as they broadcast in analog.
Another exception would be portable TVs that had some way of receiving input from an external antenna. Then you could use a DTV converter box to receive signals in conjunction with an antenna. But, DTV converters are not portable so you would have that limitation.
Digital portable TVs are far and few. Radio Shack has two 7" portable televisions capable of displaying digital signals. I recently reviewed the Accurian 7” portable handheld LCD TV and found it to be a reliable replacement for an analog portable TV.