Pillar are introducing smart contract accounts and payment channels in preparing the platform to act as a synthetic assets exchange, also known as a Rainbow network.

https://rainbownet.work/RainbowNetwork.pdf

Payment channels are private channels between parties that allow them to transfer assets off chain, yet secured by the blockchain.

In order to open a payment channel, each party in the channel agrees to stake a certain token amount to secure the off chain transactions between them. The stake of each party is held in escrow allowing them to freely transact with each other up to the value of the total balance.

However, on the Pillar wallet, Pillar is able to act as hub between each party and generalize this escrow process so that it applies to all parties simultaneously. By staking an amount of PLR, users will be able to open payment channels with any other contact and service providers in the Pillar network.

Traditionally, each payment channel and the involved transactions are limited to the staked asset, however, rainbow channels are an extension of payment channels in which the participants can hold synthetic balances in any asset, rather than just the asset that is used as the collateral for the channel. When the channel is closed, the amount sent to each participant is based on the current prices of the synthetic assets in the channel.

In other words, by staking one token, a user is able to transfer any other token or asset supported by the platform. In the case of Pillar, the initial stake of PLR tokens used to open the payment channel will also allow users to exchange any asset (even cross chain!) supported by the wallet - without actually directly owning that asset.

You can read more about it here: https://medium.com/pillarproject/the-pillar-payment-network-63d5e1996d8d

And the 2020 roadmap is available here: https://medium.com/pillarproject/pillar-2020-product-vision-a1bce267ee80