Let’s assume the goal for your Leads campaign is to encourage people to contact your business through your website. So, you’d choose Website as your conversion location and Contact as your conversion event. You’ll note that you also have Lead, Submit Application and Schedule as alternative conversion event options.
Campaigns made before the change will retain their existing objectives, and can even be duplicated with the existing objectives until the end of 2021. There is currently no word, however, on whether or not the end of the year is the hard cut off date.
As far as actual roll out on this goes, it is yet to be determined. As with most changes they make, it looks like this will be a gradual roll out across accounts. So, just sit back, relax, and keep an eye on your account for these new changes.