user63179: According to Jameson Lopp (https://www.coindesk.com/spv-support-billion-bitcoin-users-sizing-scaling-claim/), allowing pruned nodes to advertise that they support BIP 37 would be impossible without "extensive protocol changes." What changes would make this possible? 

user3697: Pruned peers do not have the full blockchain history and therefore have only limited value for SPV clients.
With Bitcoin Core 0.16, pruned peers will announce their service via NODE_NETWORK_LIMITED (see BIP159). BIP159 is not a consensus change.
This will allow SPV clients to connect to pruned peers. But, since they only signal for the last 288 blocks, SPV/BIP37 clients interested to load history older than 1 day of blocks would still require to connect to traditional peers.
In the future, pruned nodes may have a way to signal how many blocks they will keep on disk (without adding a fingerprinting vulnerability).
Note that BIP37 is a controversial concept. It has significant privacy downsides (see Jonas Nick's research).
A far better concept is "Client side filtering". See the upcoming BIP157 and BIP158.

63179: <p>According to Jameson Lopp (<a href="https://www.coindesk.com/spv-support-billion-bitcoin-users-sizing-scaling-claim/" rel="nofollow noreferrer">https://www.coindesk.com/spv-support-billion-bitcoin-users-sizing-scaling-claim/</a>), allowing pruned nodes to advertise that they support BIP 37 would be impossible without "extensive protocol changes." What changes would make this possible? </p>
 3697: <p>Pruned peers do not have the full blockchain history and therefore have only limited value for SPV clients.</p>
<p>With Bitcoin Core 0.16, pruned peers will announce their service via <code>NODE_NETWORK_LIMITED</code> (see <a href="https://github.com/bitcoin/bips/blob/master/bip-0159.mediawiki" rel="nofollow noreferrer">BIP159</a>). BIP159 is not a consensus change.</p>
<p>This will allow SPV clients to connect to pruned peers. But, since they only signal for the last 288 blocks, SPV/BIP37 clients interested to load history older than 1 day of blocks would still require to connect to traditional peers.</p>
<p>In the future, pruned nodes may have a way to signal how many blocks they will keep on disk (without adding a fingerprinting vulnerability).</p>
<p>Note that BIP37 is a controversial concept. It has significant privacy downsides (see Jonas Nick's research).</p>
<p>A far better concept is &quot;Client side filtering&quot;. See the upcoming <a href="https://github.com/bitcoin/bips/blob/master/bip-0157.mediawiki" rel="nofollow noreferrer">BIP157</a> and <a href="https://github.com/bitcoin/bips/blob/master/bip-0157.mediawiki" rel="nofollow noreferrer">BIP158</a>.</p>
