I was in the same situation, a bit worried as to what can happen if I could not travel to Australia before my IED(Subclass 190 Visa) due to Covid19 until I saw this blog, and mailed them (skilled.support@homeaffairs.gov.au) mentioning my hiccup not to turn up if this situation continues(International travel ban) and also giving all my details as in name, country, visa grant number, date of grant etc.
To my surprise I received an Automated response in a minute with the below content:
INFORMATION ON FIRST ENTRY TO AUSTRALIA
This information is only for holders of one of the following Skilled visas
Skilled Independent (subclass 189)
Skilled Nominated (subclass 190)
Skilled Regional (subclass 489)
Skilled Work Regional (subclass 491)
If you were outside Australia when you were granted one of the above Skilled visas then your visa grant will be subject to visa Condition 8504 which provides that:
The holder must enter Australia as the holder of the visa to which the condition applies before a date specified by the Minister.
This condition requires that each visa holder must make their first entry into Australia before the “For first entry, arrive by” date specified in the “Grant Notification” letter. Under the Migration Act 1958, failure to comply with visa conditions can render a visa liable for cancellation.
Skilled Migration is aware there will be circumstances when you and/or family members (who were granted a visa as part of your application) may not be able to comply with this condition, for example due to global travel restrictions.
Generally we will not seek to cancel a Skilled Migration visa where the only reason for doing so would be breach of Condition 8504.
Visa Validity Period
If you are not able to make your first entry into Australia before the “For first entry, arrive by” date you can use this
Notice when you travel to Australia during the period for which you hold a valid visa. Information about your visa
validity period is specified in the “Grant Notification” letter, as the “Must not arrive after date”.
We cannot extend the validity period of your visa, and if your Skilled Migration visa ceases for any reason then you
cannot use this notice to enter Australia as the holder of this visa.
Travelling to Australia
When you travel to Australia within the visa validity period you should present this notice to travel providers. This notice should be sufficient evidence for a travel provider to be satisfied that the visa holder can enter Australia as the holder of a Skilled Migration visa. Visa holder(s) may wish to carry a copy of this notice to present to the airline when checking in at the airport and on arrival into Australia. Please note that some delays may be encountered upon arrival into Australia while visa validity is verified…etcetera "
Anil, I hope this is some sort of extension letter.