After a fruitless and frustrating Google search to determine whether or not it was possible, I made peace with the idea that batch invoicing was not possible in the new QuickBooks Online, and that I would just have to wait until it was. A couple of days later I figured it out. Here is how to do batch invoicing in the new QuickBooks Online (QBO).
Batch invoicing in the new QuickBooks Online is done from the Transactions > Sales menu. Click on Unbilled Activity icon in the "money bar." Select the clients which you'd like to create invoices for. Choose "Create Invoices" from the Batch Actions drop down menu. Invoices will be created on today's date. There is no way to adjust the invoice date, so if you would like the invoice date to be different than today, it may be better to create the invoices individually. Otherwise you'll have to open each invoice after creating the batch of invoices, and edit them one-by-one. Perhaps this will be good motivation to get your invoices generated on the day they are supposed to be :-) Happy batch invoicing!