grep "id=" sample.svg
   id="svg2"
     id="metadata8">
     id="defs6">
       id="clipPath3342">
         id="circle3344"
     id="namedview4"
     showgrid="false"
     id="image10"
     id="path3348"
     id="image3338"
     id="path3337"

awk 'BEGIN { n=1;}  /(Wid=[^0-9]+)/ { sub(/[0-9]+/, n, $0)
++n
}
/.*/ { print }
' sample.svg | grep "id="

id="svg1"
     id="metadata2">
     id="defs3">
       id="clipPath4">
         id="circle5"
     id="namedview6"
     showgrid="false"
     id="image7"
     id="path8"
     id="image9"
     id="path10"