^^^yup, this. As LO starts to need longer A times, you can push both naps gradually later, leave the am one long and cap the pm nap shorter and shorter until you drop it entirely and the morning nap is in the middle of the day.
OR, if you're getting EWs and/or consistent complete pm nap resistance, you can cap the am nap shorter and shorter, which will mean you need to offer the pm one gradually earlier, until it is in the middle of the day and you drop the am one. Did you read the 2-1 links I posted above? There's more info there